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Mast M, Schubert H, Mayer HA, Wesemann L. Trianionic Carbocyclic NCN Pincer Ligand: Coordination Chemistry and Reactivity Studies. Inorg Chem 2024; 63:10860-10870. [PMID: 38804041 DOI: 10.1021/acs.inorgchem.4c01602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
(BCHT-NCN)H3 (1) [1,6-bis(methylene(bis-2,6-diisopropylaniline)(benzo)cycloheptatriene)] was synthesized by nucleophilic substitution treating 1,6-bis(methylenebromide)(benzo)cycloheptatriene with 2 equiv of Li[2,6-iPr2C6H3NH], Li[Dipp-NH]. Triple deprotonation of (BCHT-NCN)H3 (1) using n-BuLi yields the deprotonation product [(BCHT-NCN)Li3] (2), which crystallizes as a dimer [{[BCHT-NCN]Li3(Et2O)2}2] (2)2. Coordination compounds of the trianionic pincer ligand were obtained with SnCl2, YCl3(THF)3.5, and HfCl4(THF)2: [(BCHT-NCN)SnLi] (3), [(BCHT-NCN)Y(THF)2] (4), [(BCHT-NCN)HfCl2][Li(THF)4] (5), respectively. A hafnium hydride complex [(BCHT-NCN)HfH(HBEt3)][K(Et2O)2] (6) was isolated after reaction of 5 with K[HBEt3]. A MeNHC substitution product [(BCHT-NCN)HfCl(MeNHC)] (7) was synthesized treating compound 5 with MeNHC at rt. Following an n-BuLi reaction of 7 gives an alkyl complex [(BCHT-NCN)Hf(n-Bu)(MeNHC)] (8). Thermolysis of 7 yields the isomerization product [(BCHT-NCN#)HfCl(MeNHC)] (9), which was transferred into a methyl complex [(BCHT-NCN#)HfMe(MeNHC)] (10) upon treatment with MeMgBr. Hydride abstraction from complex 9 leads to a cationic complex [(BCHT-NCN+)HfCl(MeNHC)][Al(OtBuF)4] (11).
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Affiliation(s)
- Maximilian Mast
- Institut für Anorganische Chemie, Eberhard Karls Universität, Tübingen, Auf der Morgenstelle 18, Tübingen 72076, Germany
| | - Hartmut Schubert
- Institut für Anorganische Chemie, Eberhard Karls Universität, Tübingen, Auf der Morgenstelle 18, Tübingen 72076, Germany
| | - Hermann A Mayer
- Institut für Anorganische Chemie, Eberhard Karls Universität, Tübingen, Auf der Morgenstelle 18, Tübingen 72076, Germany
| | - Lars Wesemann
- Institut für Anorganische Chemie, Eberhard Karls Universität, Tübingen, Auf der Morgenstelle 18, Tübingen 72076, Germany
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2
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Tomsu G, Stöger B, Kirchner K. Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes. MONATSHEFTE FUR CHEMIE 2024; 155:173-181. [PMID: 38440089 PMCID: PMC10908616 DOI: 10.1007/s00706-024-03171-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 01/03/2024] [Indexed: 03/06/2024]
Abstract
The synthesis, characterization, and reactivity of several group 4 metal complexes featuring a central anionic pyrrole moiety connected via CH2 linkers to two phosphine donors is described. Treatment of [P(NH)P-iPr] with [MCl4(THF)2] (M = Zr, Hf) in the presence of base yields the dimeric complexes [M(PNPiPr)(μ-Cl)(Cl)2]2 featuring two bridging chloride ligands. These complexes react with sodium cyclopentadienyl and SiMe3I to give the mononuclear complexes [M(PNPiPr)(η5-Cp)(Cl)2] and [M(PNPiPr)(I)3], respectively. The latter react with MeMgBr to form the trialkyl complexes [M(PNPiPr)(Me)3]. Upon treatment of [Ti(NMe2)4] with [P(NH)P-iPr] a complex with the general formula [Ti(PNPiPr)(NMe2)3] is obtained. DFT calculations revealed that the most stable species is [Ti(κ1N- PNPiPr)(NMe2)3] featuring a κ1N-bound PNP ligand. When [P(NH)P-iPr] is reacted with [Ti(NMe2)4] in CH2Cl2 complex [Ti(PNPiPr)(Cl)2(NMe2)] is formed. Treatment of a solution of [P(NH)P-iPr] and [Zr(NMe2)4] with SiMe3Br affords the anionic seven-coordinate tetrabromo complex [Zr(PNPiPr)(Br)4][H2NMe2]. The corresponding hafnium complex [Hf(PNPiPr)(Br)4][H2NEt2] is obtained in similar fashion by utilizing [Hf(NEt2)4] as metal precursor. All complexes are characterized by means of NMR spectroscopy. Representative complexes were also characterized by X-ray crystallography. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s00706-024-03171-x.
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Affiliation(s)
- Gerald Tomsu
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Center, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
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3
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Tomsu G, Stöger B, Kirchner K. Pyrrole-Based Ti(III) and Ti(IV) PNP Pincer Complexes: Insertion of Ketones into the Ti(IV)-Phosphorus Bond. Organometallics 2023; 42:2999-3004. [PMID: 37886626 PMCID: PMC10598877 DOI: 10.1021/acs.organomet.3c00327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Indexed: 10/28/2023]
Abstract
The synthesis, characterization, and reactivity of pyrrole-based Ti(III) and Ti(IV) PNP pincer complexes are described. [P(NH)P-iPr] (1) reacts with [TiCl4(THF)2] at room temperature in the presence of NEt3 to afford the Ti(IV) complex [Ti(PNPiPr)(Cl)3]. This complex reacts with acetone and cyclopentanone to give complexes [Ti(PNOacet-iPr)(Cl)3] and [Ti(PNOcyclo-iPr)(Cl)3], respectively. Insertion of the ketone into the Ti(IV)-P bond took place, forming a new tridendate PNO-ligand. Treatment of [TiCl3(THF)3] with the lithium salt of [P(NH)P-iPr] afforded, upon workup, complex [Ti(PNP-iPr)(Cl)2(THF)], a paramagnetic complex with an μeff value of 1.8(1) μB which corresponds to one unpaired electron and a formal oxidation state of +III. This compound does not react with ketones. A mechanistic proposal based on DFT calculations is presented. Ketone insertion proceeds via an associative reaction initiated by ketone coordination at the metal center, followed by the opening of the five-membered chelate ring, and finally an intramolecular nucleophilic attack of the noncoordinated phosphine arm at the carbonyl atom of the ketone. All complexes were characterized by X-ray crystallography.
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Affiliation(s)
- Gerald Tomsu
- Institute
of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, A-1060 Wien, Austria
| | - Berthold Stöger
- X-ray
Center, TU Wien, Getreidemarkt
9/163, A-1060 Wien, Austria
| | - Karl Kirchner
- Institute
of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, A-1060 Wien, Austria
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4
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Schratzberger H, Liebminger LA, Stöger B, Veiros LF, Kirchner K. Base metal complexes featuring a new pyrazole-derived PCP pincer ligand. Dalton Trans 2023; 52:12410-12422. [PMID: 37594380 DOI: 10.1039/d3dt02111d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
A new pyrazole-derived PCP pincer ligand featuring a 1-methylpyrazole backbone tethered to two di(isopropyl)phosphine moieties via phenylene spacers (P(CH)P-iPr) was prepared. When reacting the ligand with group six carbonyl complexes [M(CO)6] (M = Cr, Mo, W) at 130 °C, complexes of the type [M(κ2PN-PCP-iPr)(CO)4] were obtained featuring a κ2P,N-bound ligand with a pendant phosphine arm. Upon an increase of the reaction temperature to 150 °C, in the case of molybdenum, the formation of the complex [Mo(κ3PCP-PCP-iPr)(CO)3] was observed featuring a weak Mo-C bond. DFT calculations reveal that there is no agostic η2-C-H interaction. Treatment of [Mn2(CO)10], [Fe2(CO)9], [Co2(CO)8] and [Ni(COD)2] afforded complexes [Mn(κ3PCP-PCP-iPr)(CO)3], [Fe(κ3PCP-PCP-iPr)(H)(CO)2], [Co(κ3PCP-PCP-iPr)(CO)2] and [Ni(κ3PCP-PCP-iPr)(H)], respectively, where the PCP ligand is coordinated in the typical meridional κ3-fashion. Postfunctionalization of the anionic PCP pincer ligand was possible via N-methylation of the second nitrogen atom of the pyrazole unit with the oxonium salt [Me3O]BF4. Treatment of [Mn(κ3PCP-PCP-iPr)(CO)3] and [Fe(κ3PCP-PCP-iPr)(H)(CO)2] with [Me3O]BF4 resulted in the formation of the cationic complexes [Mn(κ3PCP-PCPMe-iPr)(CO)3]+ and [Fe(κ3PCP-PCPMe-iPr)(Cl)(CO)2]+. In the case of the latter, the chloride ligand seems to originate from the solvent CH2Cl2 undergoing a hydride chloride exchange. All complexes were characterized by means of 1H, 13C{1H}, and 31P{1H} NMR spectroscopy, IR spectroscopy and HR-MS. In addition, the structures of representative complexes were determined by X-ray crystallography.
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Affiliation(s)
- Heiko Schratzberger
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9, A-1060 Vienna, Austria.
| | - Lorenzo A Liebminger
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9, A-1060 Vienna, Austria.
| | - Berthold Stöger
- X-Ray Center, TU Wien, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Luis F Veiros
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049 001 Lisboa, Portugal
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9, A-1060 Vienna, Austria.
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Schratzberger H, Himmelbauer D, Eder W, Weiser M, Stöger B, Kirchner K. Solvothermal synthesis of cobalt PCP pincer complexes from [Co 2(CO) 8]. MONATSHEFTE FUR CHEMIE 2023; 154:1253-1262. [PMID: 37927400 PMCID: PMC10620272 DOI: 10.1007/s00706-023-03123-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 08/23/2023] [Indexed: 11/07/2023]
Abstract
Treatment of [Co2(CO)8] with the ipso-substituted P(C-X)PY ligands (X = Br, Cl; R = iPr, tBu) bearing Y = NH and CH2 linkers under solvothermal conditions affords the five-coordinate Co(I) and Co(III) complexes [CoI(PCPY-R)(CO)2] and [CoIII(PCPY-R)X2]. The later are paramagnetic exhibiting a solution magnetic moment in the range of 3.0-3.3 μB which is consistent with a d6 intermediate spin system corresponding to two unpaired electrons. In the case of P(C-X)PY ligands (X = Br, Cl; R = tBu; Y = NH) the formation of the square planar Co(II) complex [Co(PCPNH-tBu)X] was favored. This complex gives rise to a magnetic moment of 1.8 μB being consistent with a d7 low spin system corresponding to one unpaired electron. All complexes are characterized by means of spectroscopic techniques (NMR, IR), HR-MS. Representative complexes were also characterized by X-ray crystallography. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s00706-023-03123-x.
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Affiliation(s)
- Heiko Schratzberger
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
| | - Daniel Himmelbauer
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
| | - Wolfgang Eder
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
| | - Michael Weiser
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Center, TU Vienna, Getreidemarkt 9/163-AC, 1060 Wien, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria
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Wei D, Shi X, Junge H, Du C, Beller M. Carbon neutral hydrogen storage and release cycles based on dual-functional roles of formamides. Nat Commun 2023; 14:3726. [PMID: 37349304 DOI: 10.1038/s41467-023-39309-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 06/07/2023] [Indexed: 06/24/2023] Open
Abstract
The development of alternative clean energy carriers is a key challenge for our society. Carbon-based hydrogen storage materials are well-suited to undergo reversible (de)hydrogenation reactions and the development of catalysts for the individual process steps is crucial. In the current state, noble metal-based catalysts still dominate this field. Here, a system for partially reversible and carbon-neutral hydrogen storage and release is reported. It is based on the dual-functional roles of formamides and uses a small molecule Fe-pincer complex as the catalyst, showing good stability and reusability with high productivity. Starting from formamides, quantitative production of CO-free hydrogen is achieved at high selectivity ( > 99.9%). This system works at modest temperatures of 90 °C, which can be easily supplied by the waste heat from e.g., proton-exchange membrane fuel cells. Employing such system, we achieve >70% H2 evolution efficiency and >99% H2 selectivity in 10 charge-discharge cycles, avoiding undesired carbon emission between cycles.
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Affiliation(s)
- Duo Wei
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
- Leibniz-Institut für Katalyse e.V, 18059, Rostock, Germany
| | - Xinzhe Shi
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
- Leibniz-Institut für Katalyse e.V, 18059, Rostock, Germany
| | - Henrik Junge
- Leibniz-Institut für Katalyse e.V, 18059, Rostock, Germany.
| | - Chunyu Du
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China.
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Kasera A, Biswas JP, Ali Alshehri A, Ahmed Al-Thabaiti S, Mokhtar M, Maiti D. Transition metal pincer complexes: A series of potential catalysts in C H activation reactions. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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8
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Eder W, Himmelbauer D, Stöger B, Veiros LF, Pignitter M, Kirchner K. Manganese and iron PCP pincer complexes - the influence of sterics on structure and reactivity. Dalton Trans 2021; 50:13915-13924. [PMID: 34528031 DOI: 10.1039/d1dt02407h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The syntheses of various manganese and iron PCP pincer complexes via a solvothermal oxidative addition methodology is described. Upon reacting [Mn2(CO)10] with the ligands (P(C-Br)PCH2-iPr) (1a) and (P(C-Br)PO-iPr) (1b), Mn(I) PCP pincer complexes [Mn(PCPCH2-iPr)(CO)3] (2a) and [Mn(-PCPO-iPr)(CO)3] (2b) were obtained. Protonation of 2a with HBF4·Et2O led to the formation of [Mn(κ3P,CH,P-P(CH)PCH2-iPr)(CO)3]BF4 (3) featuring an η2-Caryl-H agostic bond. The solvothermal reaction of 1a with [Fe2(CO)9] afforded the Fe(II) PCP pincer complex [Fe(PCPCH2-iPr)(CO)2Br] (4). Treatment of 4 with Li[HBEt3] afforded the Fe(I) complex [Fe(PCPCH2-iPr)(CO)2] (5a). When using the sterically more demanding ligands (P(C-Br)PCH2-tBu) (1c) and (P(C-Br)PO-tBu)(1d) striking differences in reactivity were observed. While neither 1c nor 1d showed any reactivity towards [Mn2(CO)10], the reaction with [Fe2(CO)9] and [Fe(CO)5] led to the formation of the Fe(I) complexes [Fe(PCPCH2-tBu)(CO)2] (5b) and [Fe(PCPO-tBu)(CO)2] (5c). X-ray structures of representative complexes are provided.
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Affiliation(s)
- Wolfgang Eder
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
| | - Daniel Himmelbauer
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
| | - Berthold Stöger
- X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Luis F Veiros
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049-001 Lisboa, Portugal
| | - Marc Pignitter
- Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
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9
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Himmelbauer D, Schratzberger H, Käfer MG, Stöger B, Veiros LF, Kirchner K. Nonsymmetrical Benzene–Pyridine-Based Nickel Pincer Complexes Featuring Borohydride, Formate, Ethyl, and Nitrosyl Ligands. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel Himmelbauer
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Heiko Schratzberger
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Matthias G. Käfer
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Luis F. Veiros
- Centro de Química Estrutural and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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Collett JD, Ransohoff RW, Krause JA, Guan H. An Iron‐Hydrogen Bond Resistant to Protonation and Oxidation. Z Anorg Allg Chem 2021. [DOI: 10.1002/zaac.202100066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Joel D. Collett
- Department of Chemistry University of Cincinnati P.O. Box 210172 Cincinnati Ohio 45221-0172 United States
| | - Rebecca W. Ransohoff
- Department of Chemistry University of Cincinnati P.O. Box 210172 Cincinnati Ohio 45221-0172 United States
| | - Jeanette A. Krause
- Department of Chemistry University of Cincinnati P.O. Box 210172 Cincinnati Ohio 45221-0172 United States
| | - Hairong Guan
- Department of Chemistry University of Cincinnati P.O. Box 210172 Cincinnati Ohio 45221-0172 United States
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Pecak J, Fleissner S, Veiros LF, Pittenauer E, Stöger B, Kirchner K. Synthesis and Catalytic Reactivity of Cobalt Pincer Nitrosyl Hydride Complexes. Organometallics 2021; 40:278-285. [PMID: 33519014 PMCID: PMC7842137 DOI: 10.1021/acs.organomet.0c00755] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Indexed: 11/30/2022]
Abstract
The synthesis, characterization, and catalytic activity of low-spin {CoNO}8 pincer complexes of the type [Co(PCP)(NO)(H)] are described. These compounds are obtained either by reacting [Co(PCP)(κ2-BH4)] with NO and Et3N or, alternatively, by reacting [Co(PCP)(NO)]+ with boranes, such as NH3·BH3 in solution. The five-coordinate, diamagnetic Co(III) complex [Co(PCPNMe-iPr)(NO)(H)] was found to be the active species in the hydroboration of alkenes with anti-Markovnikov selectivity. A range of aromatic and aliphatic alkenes were efficiently converted with pinacolborane (HBpin) under mild conditions in good to excellent yield. Mechanistic insight into the catalytic reaction is provided by means of isotope labeling, NMR spectroscopy, and APCI/ESI-MS as well as DFT calculations.
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Affiliation(s)
- Jan Pecak
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Sarah Fleissner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Luis F Veiros
- Centro de Química Estrutural and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Ernst Pittenauer
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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12
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Khusnutdinov RI, Bayguzina AR. New advances in the catalysis of organic reactions by iron compounds. RUSSIAN CHEMICAL REVIEWS 2020. [DOI: 10.1070/rcr4943] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The review summarizes and systematizes the literature data on a new promising application area of iron compounds, that is, catalysis of organic reactions. The considered reactions include halogenation, formation of C−C bonds with the participation of various substrates, new methods for the synthesis of ethers and aromatic and heteroaromatic carboxylic acid esters, N-alkylation of aliphatic and aromatic amines and amidation of olefins and cyclopropane-containing hydrocarbons. The advances in the synthesis of quinolines and unusual cyclization reactions catalyzed by iron complexes are described.
The bibliography includes 144 references.
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13
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Pecak J, Eder W, Stöger B, Realista S, Martinho PN, Calhorda MJ, Linert W, Kirchner K. Synthesis, Characterization, and Catalytic Reactivity of {CoNO} 8 PCP Pincer Complexes. Organometallics 2020; 39:2594-2601. [PMID: 32742055 PMCID: PMC7388324 DOI: 10.1021/acs.organomet.0c00167] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Indexed: 11/28/2022]
Abstract
![]()
The reaction of coordinatively
unsaturated Co(II) PCP pincer complexes
with nitric oxide leads to the formation of new, air-stable, diamagnetic mono nitrosyl compounds. The synthesis
and characterization of five- and four-coordinate Co(III) and Co(I)
nitrosyl pincer complexes based on three different ligand scaffolds
is described. Passing NO through a solution of [Co(PCPNMe-iPr)Cl], [Co(PCPO-iPr)Cl] or [Co(PCPCH2-iPr)Br] led to the
formation of the low-spin complex [Co(PCP-iPr)(NO)X]
with a strongly bent NO ligand. Treatment of the latter species with
(X = Cl, Br) AgBF4 led to chloride abstraction and formation
of cationic square-planar Co(I) complexes of the type [Co(PCP-iPr)(NO)]+ featuring a linear NO group. This
reaction could be viewed as a formal two electron reduction of the
metal center by the NO radical from Co(III) to Co(I), if NO is counted
as NO+. Hence, these systems can be described as {CoNO}8 according to the Enemark–Feltham convention. X-ray
structures, spectroscopic and electrochemical data of all nitrosyl
complexes are presented. Preliminary studies show that [Co(PCPNMe-iPr)(NO)]+ catalyzes efficiently
the reductive hydroboration of nitriles with pinacolborane (HBpin)
forming an intermediate {CoNO}8 hydride species.
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Affiliation(s)
- Jan Pecak
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Wolfgang Eder
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Sara Realista
- Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Paulo N Martinho
- BioISI - Biosystems and Integrative Sciences Institute, DQB, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Maria José Calhorda
- BioISI - Biosystems and Integrative Sciences Institute, DQB, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Wolfgang Linert
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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Abstract
Our planet urgently needs sustainable solutions to alleviate the anthropogenic global warming and climate change. Homogeneous catalysis has the potential to play a fundamental role in this process, providing novel, efficient, and at the same time eco-friendly routes for both chemicals and energy production. In particular, pincer-type ligation shows promising properties in terms of long-term stability and selectivity, as well as allowing for mild reaction conditions and low catalyst loading. Indeed, pincer complexes have been applied to a plethora of sustainable chemical processes, such as hydrogen release, CO2 capture and conversion, N2 fixation, and biomass valorization for the synthesis of high-value chemicals and fuels. In this work, we show the main advances of the last five years in the use of pincer transition metal complexes in key catalytic processes aiming for a more sustainable chemical and energy production.
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15
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Recent Advances in Homogeneous Catalysis via Metal–Ligand Cooperation Involving Aromatization and Dearomatization. Catalysts 2020. [DOI: 10.3390/catal10060635] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Recently, an increasing number of metal complex catalysts have been developed to achieve the activation or transformation of substrates based on cooperation between the metal atom and its ligands. In such “cooperative catalysis,” the ligand not only is bound to the metal, where it exerts steric and electronic effects, but also functionally varies its structure during the elementary processes of the catalytic reaction. In this review article, we focus on metal–ligand cooperation involving aromatization and dearomatization of the ligand, thus introducing the newest developments and examples of homogeneous catalytic reactions.
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16
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Wiedmaier NR, Speth H, Leistikow G, Eichele K, Schubert H, Mayer HA, Wesemann L. Conformation controlled stepwise hydride shuffling from the metal to the ligand backbone. Dalton Trans 2020; 49:7218-7227. [DOI: 10.1039/d0dt01431a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The protonation of the benzo annulated cycloheptatriene PCP pincer ruthenium hydrido dicarbonyl complex using the superacid [H(Et2O)2][BArF24] launches a cascade of hydride shifts which lead to the hydrogenation of the ligand backbone.
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Affiliation(s)
| | - Hansjörg Speth
- Institut für Anorganische Chemie
- Universität Tübingen
- 72076 Tübingen
- Germany
| | - Georg Leistikow
- Institut für Anorganische Chemie
- Universität Tübingen
- 72076 Tübingen
- Germany
| | - Klaus Eichele
- Institut für Anorganische Chemie
- Universität Tübingen
- 72076 Tübingen
- Germany
| | - Hartmut Schubert
- Institut für Anorganische Chemie
- Universität Tübingen
- 72076 Tübingen
- Germany
| | - Hermann A. Mayer
- Institut für Anorganische Chemie
- Universität Tübingen
- 72076 Tübingen
- Germany
| | - Lars Wesemann
- Institut für Anorganische Chemie
- Universität Tübingen
- 72076 Tübingen
- Germany
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17
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Himmelbauer D, Stöger B, Veiros LF, Pignitter M, Kirchner K. Cr(II) and Cr(I) PCP Pincer Complexes: Synthesis, Structure, and Catalytic Reactivity. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00651] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel Himmelbauer
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Luis F. Veiros
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049-001 Lisboa, Portugal
| | - Marc Pignitter
- Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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18
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Jackson BJ, Najera DC, Matson EM, Woods TJ, Bertke JA, Fout AR. Synthesis and Characterization of (DIPPCCC)Fe Complexes: A Zwitterionic Metalation Method and CO2 Reactivity. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00271] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Bailey J. Jackson
- School of Chemical Sciences, University of Illinois at Urbana—Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Daniel C. Najera
- School of Chemical Sciences, University of Illinois at Urbana—Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Ellen M. Matson
- School of Chemical Sciences, University of Illinois at Urbana—Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Toby J. Woods
- School of Chemical Sciences, University of Illinois at Urbana—Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Jeffery A. Bertke
- School of Chemical Sciences, University of Illinois at Urbana—Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Alison R. Fout
- School of Chemical Sciences, University of Illinois at Urbana—Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
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19
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Kurisu N, Asano E, Hatayama Y, Kurihara Y, Hashimoto T, Funatsu K, Ueda K, Yamaguchi Y. A β-Diketiminato-Based Pincer-Type Nickel(II) Complex: Synthesis and Catalytic Performance in the Cross-Coupling of Aryl Fluorides with Aryl Grignard Reagents. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201801179] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Nobutaka Kurisu
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
| | - Erika Asano
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
| | - Yuki Hatayama
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
| | - Youji Kurihara
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
| | - Toru Hashimoto
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
| | - Kei Funatsu
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
| | - Kazuyoshi Ueda
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
| | - Yoshitaka Yamaguchi
- Department of Advanced Materials Chemistry; Graduate School of Engineering; Yokohama National University; 79-5 Tokiwadai 240-8501 Hodogaya-ku, Yokohama Japan
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20
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Himmelbauer D, Mastalir M, Stöger B, Veiros LF, Kirchner K. Synthesis and Reactivity of Group Six Metal PCP Pincer Complexes: Reversible CO Addition Across the Metal–C aryl Bond. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00447] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | - Luis F. Veiros
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049-001 Lisboa, Portugal
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21
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Asano E, Hatayama Y, Kurisu N, Ohtani A, Hashimoto T, Kurihara Y, Ueda K, Ishihara S, Nagao H, Yamaguchi Y. Acetylacetonato-based pincer-type nickel(ii) complexes: synthesis and catalysis in cross-couplings of aryl chlorides with aryl Grignard reagents. Dalton Trans 2018; 47:8003-8012. [PMID: 29869657 DOI: 10.1039/c8dt01295d] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, three different types of acetylacetonato-based pincer-type nickel(ii) complexes (2) were prepared. Complex 2a possessed the tridentate ONN ligand, which was constructed by the condensation reaction of acetylacetone with N,N-diethylethylenediamine. Complex 2b contained the PPh2 donor group in contrast to the NEt2 group in 2a, i.e., an ONP ligand framework. Complex 2c was composed of the NNN ligand, which was prepared by the reaction of 4-((2,4,6-trimethylphenyl)amino)pent-3-en-2-one with N,N-diethylethylenediamine. In addition to X-ray diffraction analysis, these complexes were characterized spectroscopically. Their catalytic activity for a cross-coupling reaction of aryl halides with aryl Grignard reagents was also evaluated. Among these complexes, 2b acted as an effective catalyst for the cross-coupling reaction using aryl chlorides as electrophiles. The electronic properties of these Ni(ii) complexes were investigated by cyclic voltammetry and density functional theory calculations.
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Affiliation(s)
- Erika Asano
- Department of Advanced Materials Chemistry, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
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22
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Himmelbauer D, Mastalir M, Stöger B, Veiros LF, Pignitter M, Somoza V, Kirchner K. Iron PCP Pincer Complexes in Three Oxidation States: Reversible Ligand Protonation To Afford an Fe(0) Complex with an Agostic C–H Arene Bond. Inorg Chem 2018; 57:7925-7931. [DOI: 10.1021/acs.inorgchem.8b01018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daniel Himmelbauer
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Matthias Mastalir
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Luis F. Veiros
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049-001 Lisboa, Portugal
| | - Marc Pignitter
- Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Veronika Somoza
- Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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23
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Himmelbauer D, Stöger B, Veiros LF, Kirchner K. Reversible Ligand Protonation of a Mn(I) PCP Pincer Complex To Afford a Complex with an η2-Caryl–H Agostic Bond. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00193] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Luis F. Veiros
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049-001 Lisboa, Portugal
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24
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Tomsu G, Mastalir M, Pittenauer E, Stöger B, Allmaier G, Kirchner K. Ligand-Enforced Switch of the Coordination Mode in Low-Valent Group 6 Carbonyl Complexes Containing Pyrimidine-Based Bisphosphines. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00192] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Xia T, Wei Z, Spiegelberg B, Jiao H, Hinze S, de Vries JG. Isomerization of Allylic Alcohols to Ketones Catalyzed by Well-Defined Iron PNP Pincer Catalysts. Chemistry 2018; 24:4043-4049. [DOI: 10.1002/chem.201705454] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Indexed: 01/04/2023]
Affiliation(s)
- Tian Xia
- Leibniz-Institut für Katalyse e.V.; an der Universität Rostock; Albert-Einstein-Strasse 29a 18059 Rostock Germany
| | - Zhihong Wei
- Leibniz-Institut für Katalyse e.V.; an der Universität Rostock; Albert-Einstein-Strasse 29a 18059 Rostock Germany
| | - Brian Spiegelberg
- Leibniz-Institut für Katalyse e.V.; an der Universität Rostock; Albert-Einstein-Strasse 29a 18059 Rostock Germany
| | - Haijun Jiao
- Leibniz-Institut für Katalyse e.V.; an der Universität Rostock; Albert-Einstein-Strasse 29a 18059 Rostock Germany
| | - Sandra Hinze
- Leibniz-Institut für Katalyse e.V.; an der Universität Rostock; Albert-Einstein-Strasse 29a 18059 Rostock Germany
| | - Johannes G. de Vries
- Leibniz-Institut für Katalyse e.V.; an der Universität Rostock; Albert-Einstein-Strasse 29a 18059 Rostock Germany
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26
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Hydrogenation/Dehydrogenation of Unsaturated Bonds with Iron Pincer Catalysis. TOP ORGANOMETAL CHEM 2018. [DOI: 10.1007/3418_2018_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Polezhaev AV, Liss CJ, Telser J, Chen C, Caulton KG. A PNNH Pincer Ligand Allows Access to Monovalent Iron. Chemistry 2017; 24:1330-1341. [DOI: 10.1002/chem.201703795] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Indexed: 12/21/2022]
Affiliation(s)
| | - Cameron J. Liss
- Department of Biological, Chemical, and Physical Sciences Roosevelt University 430 S. Michigan Ave Chicago Illinois 60605 USA
| | - Joshua Telser
- Department of Biological, Chemical, and Physical Sciences Roosevelt University 430 S. Michigan Ave Chicago Illinois 60605 USA
| | - Chun‐Hsing Chen
- Department of Chemistry Indiana University Bloomington 47405 Bloomington IN USA
| | - Kenneth G. Caulton
- Department of Chemistry Indiana University Bloomington 47405 Bloomington IN USA
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28
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Dai H, Guan H. Iron Dihydride Complexes: Synthesis, Reactivity, and Catalytic Applications. Isr J Chem 2017. [DOI: 10.1002/ijch.201700101] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Huiguang Dai
- Department of Chemistry University of Cincinnati Cincinnati, OH 45221-0172 USA
| | - Hairong Guan
- Department of Chemistry University of Cincinnati Cincinnati, OH 45221-0172 USA
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29
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Kumar LM, Ansari RM, Bhat BR. Retracted
: Catalytic activity of Fe(II) and Cu(II) PNP pincer complexes for Suzuki coupling reaction. Appl Organomet Chem 2017. [DOI: 10.1002/aoc.4054] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Lolakshi Mahesh Kumar
- Catalysis and Materials Laboratory, Department of ChemistryNational Institute of Technology Karnataka Surathkal Srinivasnagar ‐575025 India
| | - Rasheeda M. Ansari
- Catalysis and Materials Laboratory, Department of ChemistryNational Institute of Technology Karnataka Surathkal Srinivasnagar ‐575025 India
| | - Badekai Ramachandra Bhat
- Catalysis and Materials Laboratory, Department of ChemistryNational Institute of Technology Karnataka Surathkal Srinivasnagar ‐575025 India
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30
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Holland AM, Oliver AG, Iluc VM. Iron pyrrole-based PNP pincer ligand complexes as catalyst precursors. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2017; 73:569-574. [DOI: 10.1107/s2053229617009287] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 06/20/2017] [Indexed: 11/10/2022]
Abstract
The structure of a pincer ligand consists of a backbone and two `arms' which typically contain a P or N atom. They are tridentate ligands that coordinate to a metal center in a meridional configuration. A series of three iron complexes containing the pyrrole-based PNP pincer ligand 2,5-bis[(diisopropylphosphanyl)methyl]pyrrolide (PNpyrP) has been synthesized. These complexes are possible precursors to new iron catalysts. {2,5-Bis[(diisopropylphosphanyl)methyl]pyrrolido-κ3
P,N,P′}carbonylchlorido(trimethylphosphane-κP)iron(II), [Fe(C18H34NP2)Cl(C3H9P)(CO)] or [Fe(PNpyrP)Cl(PMe3)(CO)], (I), has a slightly distorted octahedral geometry, with the Cl and CO ligands occupying the apical positions. {2,5-Bis[(diisopropylphosphanyl)methyl]pyrrolido-κ3
P,N,P′}chlorido(pyridine-κN)iron(II), [Fe(C18H34NP2)Cl(C5H5N)] or [Fe(PNpyrP)Cl(py)] (py is pyridine), (II), is a five-coordinate square-pyramidal complex, with the pyridine ligand in the apical position. {2,5-Bis[(diisopropylphosphanyl)methyl]pyrrolido-κ3
P,N,P′}dicarbonylchloridoiron(II), [Fe(C18H34NP2)Cl(CO)2] or [Fe(PNpyrP)Cl(CO)2], (III), is structurally similar to (I), but with the PMe3 ligand replaced by a second carbonyl ligand from the reaction of (II) with CO. The two carbonyl ligands are in a cis configuration, and there is positional disorder of the chloride and trans carbonyl ligands.
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31
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Thompson CV, Arman HD, Tonzetich ZJ. A Pyrrole-Based Pincer Ligand Permits Access to Three Oxidation States of Iron in Organometallic Complexes. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00144] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C. Vance Thompson
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, Texas 78249, United States
| | - Hadi D. Arman
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, Texas 78249, United States
| | - Zachary J. Tonzetich
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, Texas 78249, United States
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32
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Zirakzadeh A, de Aguiar SRMM, Stöger B, Widhalm M, Kirchner K. Enantioselective Transfer Hydrogenation of Ketones Catalyzed by a Manganese Complex Containing an Unsymmetrical Chiral PNP′ Tridentate Ligand. ChemCatChem 2017. [DOI: 10.1002/cctc.201700042] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Afrooz Zirakzadeh
- Institute of Applied Synthetic Chemistry; Vienna University of Technology; Getreidemarkt 9, A- 1060 Vienna Austria
| | - Sara R. M. M. de Aguiar
- Institute of Applied Synthetic Chemistry; Vienna University of Technology; Getreidemarkt 9, A- 1060 Vienna Austria
| | - Berthold Stöger
- Institute of Chemical Technologies and Analytics; Vienna University of Technology; Getreidemarkt 9, A- 1060 Vienna Austria
| | - Michael Widhalm
- Institute of Chemical Catalysis; University of Vienna; Währinger Straße 38, A- 1090 Vienna Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry; Vienna University of Technology; Getreidemarkt 9, A- 1060 Vienna Austria
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33
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Zirakzadeh A, Kirchner K, Roller A, Stöger B, Widhalm M, Morris RH. Iron(II) Complexes Containing Chiral Unsymmetrical PNP′ Pincer Ligands: Synthesis and Application in Asymmetric Hydrogenations. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00711] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Alexander Roller
- X-ray
Structure Analysis Center, University of Vienna, Währinger
Straße 42, A-1090 Wien, Austria
| | | | - Michael Widhalm
- Institute
of Chemical Catalysis, University of Vienna, Währinger Straße 38, A-1090 Wien, Austria
| | - Robert H. Morris
- Department
of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
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34
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Iron(II) complexes featuring chiral PNNP diferrocene: Synthesis and characterization of potential hydrogenation catalysts. J Organomet Chem 2016. [DOI: 10.1016/j.jorganchem.2016.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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35
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de Aguiar SRMM, Stöger B, Pittenauer E, Allmaier G, Veiros LF, Kirchner K. Arene C–H Bond Coordination versus C–H Bond Cleavage in Low-Valent Group 6 Carbonyl Pincer Complexes. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00563] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | - Luis F. Veiros
- Centro
de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais No. 1, 1049-001 Lisboa, Portugal
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36
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McLeod NA, Kuzmina LG, Korobkov I, Howard JAK, Nikonov GI. Hydridosilylamido complexes of Ta and Mo isolobal with Berry's zirconocenes: syntheses, β-Si-H agostic interactions, catalytic hydrosilylation, and insight into mechanism. Dalton Trans 2016; 45:2554-61. [PMID: 26727669 DOI: 10.1039/c5dt04548g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The syntheses of novel Group 5 and Group 6 hydrosilylamido complexes of the type R(ArN[double bond, length as m-dash])M{N((t)Bu)SiMe2-H}X (M = Ta, R = Cp; M = Mo, R = ArN; X = Cl, H, OBn, Me) are described. The various substituents in the X position seem to play the key role in determining the extent of β-agostic interaction with the Si-H bond. The Mo agostic hydrido complex (ArN[double bond, length as m-dash])2Mo{η(3)-N((t)Bu)SiMe2-H}H is a pre-catalyst for the hydrosilylation of carbonyls. The stoichiometric reaction between benzaldehyde and (ArN[double bond, length as m-dash])2Mo{η(3)-N((t)Bu)SiMe2-H}H gives the benzoxy complex (ArN[double bond, length as m-dash])2Mo{N((t)Bu)SiMe2-H}(OBn), which showed a similar catalytic reactivity compared to the parent hydride. Mechanistic studies suggest that a non-hydride mechanism is operative.
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Affiliation(s)
- Nicolas A McLeod
- Chemistry Department, Brock University, Niagara Region, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada.
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37
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Murugesan S, Kirchner K. Non-precious metal complexes with an anionic PCP pincer architecture. Dalton Trans 2016; 45:416-39. [PMID: 26608262 DOI: 10.1039/c5dt03778f] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This perspective article provides an overview of the advancements in the field of non-precious metal complexes featuring anionic PCP pincer ligands with the inclusion of aliphatic systems. It covers research from the beginning in 1976 until late 2015 and provides a summary of key developments in this area, which is, to date, limited to the metals nickel, cobalt, iron, and molybdenum. While the research in nickel PCP complexes is already quite extensive, the chemistry of cobalt, iron, and molybdenum PCP complexes is comparatively sparse. With other non-precious metals such as copper, manganese, chromium or vanadium no PCP complexes are known as yet. In the case of nickel PCP complexes already many catalytic applications such as Suzuki-Miyaura coupling, C-S cross coupling, Kharasch and Michael additions, hydrosilylation of aldehydes and ketones, cyanomethylation of aldehydes, and hydroamination of nitriles were reported. While iron PCP complexes were found to be active catalysts for the hydrosilylation of aldehydes and ketones as well as the dehydrogenation of ammonia-borane, cobalt PCP complexes were not applied to any catalytic reactions. Surprisingly, only one molybdenum PCP complex is reported, which was capable of cleaving dinitrogen to give a nitride complex. This perspective underlines that the combination of cheap and abundant metals such as nickel, cobalt, and iron with PCP pincer ligands may result in the development of novel, versatile, and efficient catalysts for atom-efficient catalytic reactions.
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Affiliation(s)
- Sathiyamoorthy Murugesan
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
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38
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Mastalir M, de Aguiar SRMM, Glatz M, Stöger B, Kirchner K. A Convenient Solvothermal Synthesis of Group 6 PNP Pincer Tricarbonyl Complexes. Organometallics 2016. [DOI: 10.1021/acs.organomet.5b00940] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthias Mastalir
- Institute of Applied
Synthetic Chemistry and ‡Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Sara R. M. M. de Aguiar
- Institute of Applied
Synthetic Chemistry and ‡Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Mathias Glatz
- Institute of Applied
Synthetic Chemistry and ‡Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Berthold Stöger
- Institute of Applied
Synthetic Chemistry and ‡Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied
Synthetic Chemistry and ‡Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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39
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Zirakzadeh A, Kirchner K, Roller A, Stöger B, Carvalho MD, Ferreira LP. Synthesis, coordination behavior and structural features of chiral iron(ii) PNP diferrocene complexes. RSC Adv 2016. [DOI: 10.1039/c5ra26493f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
New chiral PNP and PNHP ferrocene ligands and the corresponding Fe(ii) complexes of PNP ligands with the general formula [Fe(PNP)X2] (X = Cl, Br) were synthesized.
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Affiliation(s)
- Afrooz Zirakzadeh
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Alexander Roller
- X-ray Structure Analysis Centre
- University of Vienna
- A-1090 Wien
- Austria
| | - Berthold Stöger
- Institute of Chemical Technologies and Analytics
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Maria Deus Carvalho
- Centro de Química e Bioquímica
- Faculdade de Ciências
- Universidade de Lisboa
- 1749-016 Lisboa
- Portugal
| | - Liliana P. Ferreira
- Biosystems and Integrative Sciences Institute
- Faculdade de Ciências
- Universidade de Lisboa
- 1749-016 Lisboa
- Portugal
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40
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Bauer G, Hu X. Recent developments of iron pincer complexes for catalytic applications. Inorg Chem Front 2016. [DOI: 10.1039/c5qi00262a] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Iron pincer complexes exhibit excellent activity in homogeneous catalysis.
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Affiliation(s)
- Gerald Bauer
- Laboratory of Inorganic Synthesis and Catalysis
- Institute of Chemical Sciences and Engineering
- École Polytechnique Fédérale de Lausanne (EPFL)
- 1015 Lausanne
- Switzerland
| | - Xile Hu
- Laboratory of Inorganic Synthesis and Catalysis
- Institute of Chemical Sciences and Engineering
- École Polytechnique Fédérale de Lausanne (EPFL)
- 1015 Lausanne
- Switzerland
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41
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Affiliation(s)
- Anubendu Adhikary
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Hairong Guan
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
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42
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Glatz M, Holzhacker C, Bichler B, Mastalir M, Stöger B, Mereiter K, Weil M, Veiros LF, Mösch‐Zanetti NC, Kirchner K. Fe
II
Carbonyl Complexes Featuring Small to Bulky PNP Pincer Ligands – Facile Substitution of κ
2
P
,
N
‐Bound PNP Ligands by Carbon Monoxide. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500646] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mathias Glatz
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria, http://www.ias.tuwien.ac.at
| | - Christian Holzhacker
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria, http://www.ias.tuwien.ac.at
| | - Bernhard Bichler
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria, http://www.ias.tuwien.ac.at
| | - Matthias Mastalir
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria, http://www.ias.tuwien.ac.at
| | - Berthold Stöger
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
| | - Kurt Mereiter
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
| | - Matthias Weil
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
| | - Luis F. Veiros
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049‐001 Lisboa, Portugal
| | | | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria, http://www.ias.tuwien.ac.at
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43
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Toda T, Kuwata S, Ikariya T. Synthesis and Structures of Ruthenium and Iron Complexes Bearing an Unsymmetrical Pincer-type Ligand with Protic Pyrazole and Tertiary Aminoalkyl Arms. Z Anorg Allg Chem 2015. [DOI: 10.1002/zaac.201500558] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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44
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Holzhacker C, Stöger B, Carvalho MD, Ferreira LP, Pittenauer E, Allmaier G, Veiros LF, Realista S, Gil A, Calhorda MJ, Müller D, Kirchner K. Synthesis and reactivity of TADDOL-based chiral Fe(II) PNP pincer complexes-solution equilibria between κ(2)P,N- and κ(3)P,N,P-bound PNP pincer ligands. Dalton Trans 2015; 44:13071-86. [PMID: 26104487 DOI: 10.1039/c5dt00832h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Treatment of anhydrous FeX2 (X = Cl, Br) with 1 equiv. of the asymmetric chiral PNP pincer ligands PNP-R,TAD (R = iPr, tBu) with an R,R-TADDOL (TAD) moiety afforded complexes of the general formula [Fe(PNP)X2]. In the solid state these complexes adopt a tetrahedral geometry with the PNP ligand coordinated in κ(2)P,N-fashion, as shown by X-ray crystallography and Mössbauer spectroscopy. Magnetization studies led to a magnetic moment very close to 4.9μB reflecting the expected four unpaired d-electrons (quintet ground state). In solution there are equilibria between [Fe(κ(3)P,N,P-PNP-R,TAD)X2] and [Fe(κ(2)P,N-PNP-R,TAD)X2] complexes, i.e., the PNP-R,TAD ligand is hemilabile. At -50 °C these equilibria are slow and signals of the non-coordinated P-TAD arm of the κ(2)P,N-PNP-R,TAD ligand can be detected by (31)P{(1)H} NMR spectroscopy. Addition of BH3 to a solution of [Fe(PNP-iPr,TAD)Cl2] leads to selective boronation of the pendant P-TAD arm shifting the equilibrium towards the four-coordinate complex [Fe(κ(2)P,N-PNP-iPr,TAD(BH3))Cl2]. DFT calculations corroborate the existence of equilibria between four- and five-coordinated complexes. Addition of CO to [Fe(PNP-iPr,TAD)X2] in solution yields the diamagnetic octahedral complexes trans-[Fe(κ(3)P,N,P-PNP-iPr,TAD)(CO)X2], which react further with Ag(+) salts in the presence of CO to give the cationic complexes trans-[Fe(κ(3)P,N,P-PNP-iPr,TAD)(CO)2X](+). CO addition most likely takes place at the five coordinate complex [Fe(κ(3)P,N,P-PNP-iPr,TAD)X2]. The mechanism for the CO addition was also investigated by DFT and the most favorable path obtained corresponds to the rearrangement of the pincer ligand first from a κ(2)P,N- to a κ(3)P,N,P-coordination mode followed by CO coordination to [Fe(κ(3)P,N,P-PNP-iPr,TAD)X2]. Complexes bearing tBu substituents do not react with CO. Moreover, in the solid state none of the tetrahedral complexes are able to bind CO.
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Affiliation(s)
- Christian Holzhacker
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
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45
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Chakraborty S, Bhattacharya P, Dai H, Guan H. Nickel and iron pincer complexes as catalysts for the reduction of carbonyl compounds. Acc Chem Res 2015; 48:1995-2003. [PMID: 26098431 DOI: 10.1021/acs.accounts.5b00055] [Citation(s) in RCA: 300] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The reductions of aldehydes, ketones, and esters to alcohols are important processes for the synthesis of chemicals that are vital to our daily life, and the reduction of CO2 to methanol is expected to provide key technology for carbon management and energy storage in our future. Catalysts that affect the reduction of carbonyl compounds often contain ruthenium, osmium, or other precious metals. The high and fluctuating price, and the limited availability of these metals, calls for efforts to develop catalysts based on more abundant and less expensive first-row transition metals, such as nickel and iron. The challenge, however, is to identify ligand systems that can increase the thermal stability of the catalysts, enhance their reactivity, and bypass the one-electron pathways that are commonly observed for first-row transition metal complexes. Although many other strategies exist, this Account describes how we have utilized pincer ligands along with other ancillary ligands to accomplish these goals. The bis(phosphinite)-based pincer ligands (also known as POCOP-pincer ligands) create well-defined nickel hydride complexes as efficient catalysts for the hydrosilylation of aldehydes and ketones and the hydroboration of CO2 to methanol derivatives. The hydride ligands in these complexes are substantially nucleophilic, largely due to the enhancement by the strongly trans-influencing aryl groups. Under the same principle, the pincer-ligated nickel cyanomethyl complexes exhibit remarkably high activity (turnover numbers up to 82,000) for catalytically activating acetonitrile and the addition of H-CH2CN across the C═O bonds of aldehydes without requiring a base additive. Cyclometalation of bis(phosphinite)-based pincer ligands with low-valent iron species "Fe(PR3)4" results in diamagnetic Fe(II) hydride complexes, which are active catalysts for the hydrosilylation of aldehydes and ketones. Mechanistic investigation suggests that the hydride ligand is not delivered to the carbonyl substrates but is important to facilitate ligand dissociation prior to substrate activation. In the presence of CO, the amine-bis(phosphine)-based pincer ligands are also able to stabilize low-spin Fe(II) species. Iron dihydride complexes supported by these ligands are bifunctional as both the FeH and NH moieties participate in the reduction of C═O bonds. These iron pincer complexes are among the first iron-based catalysts for the hydrogenation of esters, including fatty acid methyl esters, which find broad applications in industry. Our studies demonstrate that pincer ligands are promising candidates for promoting the first-row transition metal-catalyzed reduction of carbonyl compounds with high efficiency. Further efforts in this research area are likely to lead to more efficient and practical catalysts.
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Affiliation(s)
- Sumit Chakraborty
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Papri Bhattacharya
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Huiguang Dai
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Hairong Guan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
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46
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de Aguiar SRMM, Öztopcu Ö, Stöger B, Mereiter K, Veiros LF, Pittenauer E, Allmaier G, Kirchner K. Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes. Dalton Trans 2015; 43:14669-79. [PMID: 25142749 DOI: 10.1039/c4dt01932f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the present study a series of six-coordinate neutral 16e halocarbonyl Mo(ii) complexes of the type [Mo(PNP(Me)-iPr)(CO)X2] (X = I, Br, Cl), featuring the PNP pincer ligand N,N'-bis(diisopropylphosphino)-N,N'-dimethyl-2,6-diaminopyridine (PNP(Me)-iPr), were prepared and fully characterized. The synthesis of these complexes was accomplished by different methodologies depending on the halide ligands. For X = I and Br, [Mo(PNP(Me)-iPr)(CO)I2] and [Mo(PNP(Me)-iPr)(CO)Br2] were obtained by reacting [Mo(PNP(Me)-iPr)(CO)3] with stoichiometric amounts of I2 and Br2, respectively. In the case of X = Cl, [Mo(PNP(Me)-iPr)(CO)Cl2] was afforded by the reaction of [Mo(CO)4(μ-Cl)Cl]2 with 1 equiv. of PNP(Me)-iPr. The equivalent procedure also worked for X = Br. The modification of the 2,6-diaminopyridine scaffold by introducing NMe instead of NH spacers between the aromatic pyridine ring and the phosphine moieties changed the steric properties of the PNP-iPr ligand significantly. While in the present case exclusively neutral six-coordinate complexes of the type [Mo(PNP(Me)-iPr)(CO)X2] were obtained, with the parent PNP-iPr ligand, i.e. featuring NH spacers, cationic seven-coordinate complexes of the type [Mo(PNP-iPr)(CO)3X]X were afforded. Upon treatment of [Mo(PNP(Me)-iPr)(CO)X2] (X = Br, Cl) with Ag(+) in CH3CN, the cationic complexes [Mo(PNP(Me)-iPr)(CO)(CH3CN)X](+) were formed. Halide abstraction from [Mo(PNP(Me)-iPr)(CO)Cl2] in THF-CH2Cl2 afforded [Mo(PNP(Me)-iPr)(CO)(THF)Cl](+). In keeping with the facile synthesis of monocationic complexes preliminary ESI-MS and DFT/B3LYP studies revealed that one halide ligand in complexes [Mo(PNP(Me)-iPr)(CO)X2] is labile forming cationic fragments [Mo(PNP(Me)-iPr)(CO)X](+) which react with molecular oxygen in parallel pathways to yield mono and dioxo Mo(iv) and Mo(vi) species. Structures of representative complexes were determined by X-ray single crystal analyses.
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Affiliation(s)
- Sara R M M de Aguiar
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
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47
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Bichler B, Glatz M, Stöger B, Mereiter K, Veiros LF, Kirchner K. An iron(II) complex featuring κ(3) and labile κ(2)-bound PNP pincer ligands - striking differences between CH2 and NH spacers. Dalton Trans 2015; 43:14517-9. [PMID: 25138445 DOI: 10.1039/c4dt01933d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Treatment of anhydrous FeCl2 with 2 equiv. of the pincer ligand PNP-Ph afforded the diamagnetic cationic octahedral complex [Fe(κ(3)-P,N,P-PNP)(κ(2)-P,N-PNP)Cl](+) featuring a κ(2)-P,N-bound PNP ligand. Preliminary reactivity studies revealed that the κ(2)-P,N-bound PNP ligand is labile reacting with CO to afford trans-[Fe(PNP-Ph)(CO)2Cl](+).
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Affiliation(s)
- Bernhard Bichler
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
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48
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Affiliation(s)
- Ingmar Bauer
- Department Chemie, Technische Universität Dresden, Bergstraße 66, 01069 Dresden, Germany
| | - Hans-Joachim Knölker
- Department Chemie, Technische Universität Dresden, Bergstraße 66, 01069 Dresden, Germany
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49
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Samanta S, Demesko S, Dechert S, Meyer F. A two-in-one pincer ligand and its diiron(II) complex showing spin state switching in solution through reversible ligand exchange. Angew Chem Int Ed Engl 2015; 54:583-7. [PMID: 25412962 DOI: 10.1002/anie.201408966] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Indexed: 11/09/2022]
Abstract
A novel pyrazolate-bridged ligand providing two {PNN} pincer-type compartments has been synthesized. Its diiron(II) complex LFe2(OTf)3(CH3CN) (1; Tf = triflate) features, in solid state, two bridging triflate ligands, with a terminal triflate and a MeCN ligand completing the octahedral coordination spheres of the two high-spin metal ions. In MeCN solution, 1 is shown to undergo a sequential, reversible, and complete spin transition to the low-spin state upon cooling. Detailed UV/Vis and (19)F NMR spectroscopic studies as well as magnetic measurements have unraveled that spin state switching correlates with a rapid multistep triflate/MeCN ligand exchange equilibrium. The spin transition temperature can be continuously tuned by varying the triflate concentration in solution.
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Affiliation(s)
- Subhas Samanta
- Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 4, 37077 Göttingen (Germany) http://www.meyer.chemie.uni-goettingen.de
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50
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Glatz M, Bichler B, Mastalir M, Stöger B, Weil M, Mereiter K, Pittenauer E, Allmaier G, Veiros LF, Kirchner K. Iron(ii) complexes featuring κ3- and κ2-bound PNP pincer ligands – the significance of sterics. Dalton Trans 2015; 44:281-94. [PMID: 25376759 DOI: 10.1039/c4dt02866j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of octahedral Fe(ii) complexes of the type [Fe(κ3-P,N,P-PNP)(κ2-P,N-PNP)X]+ (X = Cl, Br) where PNP pincer ligands are coordinated both in a κ3-P,N,P- and κ2-P,N-fashion was prepared and characterized.
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Affiliation(s)
- Mathias Glatz
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Bernhard Bichler
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Matthias Mastalir
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Berthold Stöger
- Institute of Chemical Technologies and Analytics
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Matthias Weil
- Institute of Chemical Technologies and Analytics
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Kurt Mereiter
- Institute of Chemical Technologies and Analytics
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Ernst Pittenauer
- Institute of Chemical Technologies and Analytics
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Günter Allmaier
- Institute of Chemical Technologies and Analytics
- Vienna University of Technology
- A-1060 Vienna
- Austria
| | - Luis F. Veiros
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- A-1060 Vienna
- Austria
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