1
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Li S, Schröder M, Prudlik A, Shi X, Spannenberg A, Rabeah J, Francke R, Corzilius B, Reiß F, Beweries T. A General Concept for the Electronic and Steric Modification of 1-Metallacyclobuta-2,3-dienes: A Case Study of Group 4 Metallocene Complexes. Chemistry 2024; 30:e202400708. [PMID: 38529695 DOI: 10.1002/chem.202400708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 03/27/2024]
Abstract
The synthesis of group 4 metal 1-metallacyclobuta-2,3-dienes as organometallic analogues of elusive 1,2-cyclobutadiene has so far been limited to SiMe3 substituted examples. We present the synthesis of two Ph substituted dilithiated ligand precursors for the preparation of four new 1-metallacyclobuta-2,3-dienes [rac-(ebthi)M] (M=Ti, Zr; ebthi=1,2-ethylene-1,10-bis(η5-tetrahydroindenyl)). The organolithium compounds [Li2(RC3Ph)] (1 b: R=Ph, 1 c: R=SiMe3) as well as the metallacycles of the general formula [rac-(ebthi)M(R1C3R2)] (2 b: M=Ti, R1=R2=Ph, 2 c: M=Ti, R1=Ph, R2=SiMe3; 3 b: M=Zr, R1=R2=Ph; 3 c: M=Zr, R1=Ph, R2=SiMe3) were fully characterised. Single crystal X-ray diffraction and quantum chemical bond analysis of the Ti and Zr complexes reveal ligand influence on the biradicaloid character of the titanocene complexes. X-band EPR spectroscopy of structurally similar Ti complexes [rac-(ebthi)Ti(Me3SiC3SiMe3)] (2 a), 2 b, and 2 c was carried out to evaluate the accessibility of an EPR active triplet state. Cyclic voltammetry shows that introduction of Ph groups renders the complexes easier to reduce. 13C CPMAS NMR analysis provides insights into the cause of the low field shift of the resonances of metal-bonded carbon atoms and provides evidence of the absence of the β-C-Ti interaction.
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Affiliation(s)
- Sihan Li
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Mirjam Schröder
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Institute of Chemistry, 18059, Rostock, Germany
- University of Rostock, Department LL&M, 18059, Rostock, Germany
| | - Adrian Prudlik
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Institute of Chemistry, 18059, Rostock, Germany
| | - Xinzhe Shi
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | - Anke Spannenberg
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Jabor Rabeah
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Robert Francke
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Björn Corzilius
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Institute of Chemistry, 18059, Rostock, Germany
- University of Rostock, Department LL&M, 18059, Rostock, Germany
| | - Fabian Reiß
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Torsten Beweries
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Department LL&M, 18059, Rostock, Germany
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2
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Petrov A, Wellnitz T, Hennersdorf F, Reiß F, Hering-Junghans C. On Haptotropic Rearrangements of Diphosphene and Diarsene Ligands in Titanium Complexes. Chemistry 2024; 30:e202400575. [PMID: 38391154 DOI: 10.1002/chem.202400575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 02/23/2024] [Accepted: 02/23/2024] [Indexed: 02/24/2024]
Abstract
Dipnictenes of the type RE=ER (E=P, As, Sb, Bi) are the isovalence electronic heavier analogs of alkenes. Although diphosphenes and dipnictenes in general show a variety of binding modes in metal complexes, little is known about haptotropic shift reactions involving these ligands. Herein, we report an unprecedented η2 to η1 rearrangement of the dipnictene ligands in titanocene complexes of the type Cp2Ti(Pn2Ar2) (Pn=P, As; Ar=2,4,6-Me3-C6H2, Mes; 2,6-iPr2-C6H3, Dip; 2,4,6-iPr3-C6H2, Tip), initiated by Lewis basic ligands (L=MeCN, PMe3, AdNC, CO). In the presence of L the dipnictene ligand changes its hapticity from η2 to η1 and complexes of the general form Cp2Ti(L)(Pn2Ar2) with a succinctly different electronic structure are obtained. Electronically, the new complexes are best described as biradicaloids with antiferromagnetically coupled (via a π-bond) [Cp2TiIII]⋅+ and [Pn2Ar2]⋅- fragments. However, the biradical character of these systems is affected by the electronic features of the co-ligand and significantly decreases moving from PMe3/MeCN (σ-donors) to CNAd/CO (σ-donors/π-acceptors).
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Affiliation(s)
- Andrey Petrov
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Straße 3a, 18059, Rostock, Germany
| | - Tim Wellnitz
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Straße 3a, 18059, Rostock, Germany
- Current address: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | | | - Fabian Reiß
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Straße 3a, 18059, Rostock, Germany
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3
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Hu C, Wang XF, Li J, Chang XY, Liu LL. A stable rhodium-coordinated carbene with a σ 0π 2 electronic configuration. Science 2024; 383:81-85. [PMID: 38175894 DOI: 10.1126/science.adk6533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 11/20/2023] [Indexed: 01/06/2024]
Abstract
Isolable singlet carbenes have universally adopted a σ2π0 electronic state, making them σ-donors and π-acceptors. We present a rhodium-coordinated, cationic cyclic diphosphinocarbene with a σ0π2 ground state configuration. Nuclear magnetic resonance spectroscopy studies show a carbene carbon chemical shift below -30.0 parts per million. X-ray crystallography reveals a planar RhP2C configuration. Quantum chemical calculations rationalize how σ-electron delocalization/donation and π-electron negative hyperconjugation together stabilize the formally vacant σ orbital and the filled π orbital at the carbene center. In contrast to traditional carbene counterparts this carbene can undergo synthetic transformations with both a Lewis base and a silver salt, producing a Lewis acid/base adduct and a silver π-complex, respectively. Exhibiting ambiphilic reactivity, it can also form a ketenimine through reaction with an isocyanide.
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Affiliation(s)
- Chaopeng Hu
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Xin-Feng Wang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Jiancheng Li
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Xiao-Yong Chang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Liu Leo Liu
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
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4
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Kim J, Egger DT, Frye CW, Beaumier EP, Tonks IA. Cp 2Ti(II) Mediated Rearrangement of Cyclopropyl Imines. Organometallics 2023; 42:1331-1338. [PMID: 37915831 PMCID: PMC10619969 DOI: 10.1021/acs.organomet.3c00032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
Abstract
Ti-catalyzed oxidative alkyne carboamination with alkenes and azo compounds can yield either α,β-unsaturated imines or cyclopropyl imines through a common azatitanacyclohexene intermediate. Herein, we report the synthesis of a model azatitanacyclohexene complex (3) through the ring-opening of a cyclopropyl imine with Cp2Ti(BTMSA) (BTMSA = bis(trimethylsilyl)acetylene). 3 readily undergoes thermal or reductant-catalyzed ring contraction to an azatitanacyclopentene (4), analogous to the proposed mechanism for forming α,β-unsaturated imines in the catalytic reaction. A cyclopropyl imine or an α,β-unsaturated imine could be liberated via the oxidation of 3 or 4 with azobenzene, respectively, further implicating the role of these metallacycles in the Ti-catalyzed carboamination reaction.
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Affiliation(s)
- Jaekwan Kim
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Dominic T. Egger
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Connor W. Frye
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Evan P. Beaumier
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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5
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Brehm PC, Frontera A, Streubel R. On metal coordination of neutral open-shell P-ligands focusing on phosphanoxyls, their electron residence and reactivity. Chem Commun (Camb) 2022; 58:6270-6279. [PMID: 35579028 DOI: 10.1039/d2cc01302a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This feature article highlights the discovery and development of phosphanoxyl complex chemistry starting from (neutral) low-coordinate phosphorus radicals and the quest of metal ligation effects. We describe synthesis and reactions of precursors, namely 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) substituted phosphane tungsten(0) complexes. Trapping reactions of transient phosphanoxyl complexes, formed via thermal homolytic N-O bond cleavage, as well as their use in radical polymerisations are illustrated, thus revealing an interesting reactivity dichotomy. DFT calculations provide insight into thermal stabilities of precursors and the resulting spin density distributions (SDDs) in these reactive intermediates. Systematic studies on the dependance of the electron delocalisation in phosphanoxyl complexes have been performed examining different substitution pattern at phosphorus and different co-ligand combinations at the tungsten(0) center. Preliminary results on Mn and Fe complexes are reported.
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Affiliation(s)
- Philipp C Brehm
- Institut für Anorganische Chemie, der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany.
| | - Antonio Frontera
- Department of Chemistry, University of the Balearic Islands, Cra. de Valldemossa, 07122 Palma, Baleares, Spain
| | - Rainer Streubel
- Institut für Anorganische Chemie, der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany.
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6
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Brehm PC, Müller-Feyen AS, Schnakenburg G, Streubel R. 1,3,2-Diheterophospholane complexes: access to new tuneable precursors of phosphanoxyl complexes and P-functional polymers. Dalton Trans 2022; 51:4400-4405. [PMID: 35195141 DOI: 10.1039/d2dt00027j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Synthesis of a testbed of P-H functional diheterophospholane complexes (3 and 6a,b) with no or little steric bulk at the α-position was achieved using [NEt4][WH(CO)5] as a combined reductant and complexation reagent. Reaction with TEMPO leads to P-OTEMP substituted tungsten complexes (4 and 7a,b) possessing different thermostabilities towards N-O bond cleavage. The transient phosphanoxyl complexes obtained were used for the polymerisation of styrene and acrylonitrile. DFT calculations were performed on the formation of various open-shell complexes and Loewdin spin density distributions.
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Affiliation(s)
- Philipp C Brehm
- Institut für Anorganische Chemie, der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany.
| | - Anne S Müller-Feyen
- Institut für Anorganische Chemie, der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany.
| | - Gregor Schnakenburg
- Institut für Anorganische Chemie, der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany.
| | - Rainer Streubel
- Institut für Anorganische Chemie, der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany.
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7
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Dubey G, Mahawar N, Singh T, Saha N, Sahoo SC, Bharatam PV. Thiazetidin-2-ylidenes as four membered N-heterocyclic carbenes: theoretical studies and the generation of complexes with N + center. Phys Chem Chem Phys 2022; 24:629-633. [PMID: 34933326 DOI: 10.1039/d1cp04732a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Thiazetidin-2-ylidenes have been designed as four membered N-heterocyclic carbenes (NHCs) using quantum chemical studies. These species are smaller analogs of thiazol-2-ylidenes, possess high singlet stability (57 kcal mol-1) and large nucleophilicity (3.4 eV). The possible existence of these carbenes has been established by synthesizing and crystalizing compounds with NHC→N+←(thiazetidin-2-ylidene) coordination bonds.
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Affiliation(s)
- Gurudutt Dubey
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Nutan Mahawar
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Tejender Singh
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Nirjhar Saha
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Subash C Sahoo
- Department of Chemistry, Panjab University, Sector 14, Chandigarh, 160014, India
| | - Prasad V Bharatam
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
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8
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Shi X, Li S, Reiß M, Spannenberg A, Holtrichter-Rößmann T, Reiß F, Beweries T. 1-Zirconacyclobuta-2,3-dienes: synthesis of organometallic analogs of elusive 1,2-cyclobutadiene, unprecedented intramolecular C-H activation, and reactivity studies. Chem Sci 2021; 12:16074-16084. [PMID: 35024129 PMCID: PMC8672727 DOI: 10.1039/d1sc06052j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 11/22/2021] [Indexed: 01/25/2023] Open
Abstract
The structure, bonding, and reactivity of small, highly unsaturated ring systems is of fundamental interest for inorganic and organic chemistry. Four-membered metallacyclobuta-2,3-dienes, also referred to as metallacycloallenes, are among the most exotic examples for ring systems as these represent organometallic analogs of 1,2-cyclobutadiene, the smallest cyclic allene. Herein, the synthesis of the first examples of 1-zirconacyclobuta-2,3-dienes of the type [Cp'2Zr(Me3SiC3SiMe3)] (Cp'2 = rac-(ebthi), (ebthi = 1,2-ethylene-1,1'-bis(η5-tetrahydroindenyl)) (2a); rac-Me2Si(thi)2, thi = (η5-tetrahydroindenyl), (2b)) is presented. Both complexes undergo selective thermal C-H activation at the 7-position of the ansa-cyclopentadienyl ligand to produce a new type of "tucked-in" zirconocene system, 3a and 3b, that possesses a η3-propargyl/allenyl ligand. Both types of complexes react with carbonyl compounds, producing enynes in the case of 2a and 2b, as well as η1-allenyl complexes for 3a and 3b. Computational analysis of the structure and bonding of 2a and 3a reveals significant differences to a previously described related Ti complex. All complexes were fully characterised, including X-ray crystallography and experimental results were supported by DFT analysis.
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Affiliation(s)
- Xinzhe Shi
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Sihan Li
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Melanie Reiß
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Anke Spannenberg
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | | | - Fabian Reiß
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Torsten Beweries
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
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9
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Lv ZJ, Liu W, Zhu M, Chai Z, Wei J, Zhang WX. Insertion Chemistry of Lutetacyclopropene toward Unsaturated C-O/C-N Bonds. Chemistry 2021; 27:16498-16504. [PMID: 34608685 DOI: 10.1002/chem.202103065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Indexed: 11/08/2022]
Abstract
Although the reaction chemistry of transition metallacyclopropenes has been well-established in the last decades, the reactivity of rare-earth metallacyclopropenes remains elusive. Herein, we report the reaction of lutetacyclopropene 1 toward a series of unsaturated molecules. The reaction of 1 with one equiv. of PhCOMe, Ar1 CHO (Ar1 =2,6-Me2 C6 H3 ), W(CO)6 , and PhCH=NPh provided oxalutetacyclopentenes, metallacyclic lutetoxycarbene, and azalutetacyclopentene via 1,2-insertion of C=O, C≡O, or C=N bonds into Lu-Csp2 bond, respectively. However, the reaction between 1 and Ar2 N=C=NAr2 (Ar2 =4-MeC6 H4 ) gave an acyclic lutetium complex with a diamidinate ligand by the coupling of one molecule of 1 with two carbodiimides, irrespective of the amount of carbodiimide employed. More interestingly, when 1 was treated with two equiv. of Ar1 CHO, the reductive coupling of two C=O bonds was discovered to give a lutetium pinacolate complex along with the release of tolan. Remarkably, the reactivity of 1 is significantly different from that of scandacyclopropenes; these metallacycles derived from 1 all represent the first cases in rare-earth organometallic chemistry.
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Affiliation(s)
- Ze-Jie Lv
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Wei Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Miaomiao Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Zhengqi Chai
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
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10
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Lv ZJ, Zhu M, Liu W, Chai Z, Wei J, Zhang WX. Reactivity of Lutetacyclopropene toward Benzyl, Benzoyl, and Trimethylsilyl Nitriles Affording Diversified Lutetium Complexes. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ze-Jie Lv
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Miaomiao Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wei Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Zhengqi Chai
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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11
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London HC, Whittemore TJ, Gale AG, McMillen CD, Pritchett DY, Myers AR, Thomas HD, Shields GC, Wagenknecht PS. Ligand-to-Metal Charge-Transfer Photophysics and Photochemistry of Emissive d 0 Titanocenes: A Spectroscopic and Computational Investigation. Inorg Chem 2021; 60:14399-14409. [PMID: 34495657 DOI: 10.1021/acs.inorgchem.1c02182] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Complexes with ligand-to-metal charge-transfer (LMCT) excited states involving d0 metals represent a new design for photocatalysts. Herein, the photochemistry and photophysics of d0 titanocenes of the type Cp2Ti(C2R)2, where C2R = ethynylphenyl (C2Ph), 4-ethynyldimethylaniline (C2DMA), or 4-ethynyltriphenylamine (C2TPA), have been investigated. Cp2Ti(C2Ph)2 and Cp2Ti(C2DMA)2 have also been characterized by single-crystal X-ray diffraction. The two aryl rings in Cp2Ti(C2DMA)2 are nearly face-to-face in the solid state, whereas they are mutually perpendicular for Cp2Ti(C2Ph)2. All three complexes are brightly emissive at 77 K but photodecompose at room temperature when irradiated into their lowest-energy absorption band. The emission wavelengths and photodecomposition quantum yields are as follows: Cp2Ti(C2Ph)2, 575 nm and 0.65; Cp2Ti(C2TPA)2, 642 nm and 0.42; Cp2Ti(C2DMA)2, 672 nm and 0.25. Extensive benchmarking of the density functional theory (DFT) model against the structural data and of the time-dependent DFT (TDDFT) model against the absorption and emission data was performed using combinations of 13 different functionals and 4 basis sets. The model that predicted the absorption and emission data with the greatest fidelity utilized MN15/LANL2DZ for both the DFT optimization and the TDDFT. Computational analysis shows that absorption involves a transition to a 1LMCT state. Whereas the spectroscopic data for Cp2Ti(C2TPA)2 and Cp2Ti(C2DMA)2 are well modeled using the optimized structure of these complexes, Cp2Ti(C2Ph)2 required averaging of the spectra from multiple rotamers involving rotation of the Ph rings. Consistent with this finding, an energy scan of all rotamers showed a very flat energetic surface, with less than 1.3 kcal/mol separating the minimum and maximum. The computational data suggest that emission occurs from a 3LMCT state. Optimization of the 3LMCT state demonstrates compression of the C-Ti-C bond angle, consistent with the known products of photodecomposition.
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Affiliation(s)
- Henry C London
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Thomas J Whittemore
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Ariel G Gale
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Colin D McMillen
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - David Y Pritchett
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Alexis R Myers
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Hannah D Thomas
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - George C Shields
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Paul S Wagenknecht
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
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12
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McGeachie LJR, Bühl M, Cordes DB, Slawin AMZ, Woollins JD. Bridging (Thionylimido)metal Complexes. Inorg Chem 2021; 60:8423-8427. [PMID: 34043915 DOI: 10.1021/acs.inorgchem.1c00725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the first examples of the thionylimido ligand acting as a μ2-bridging ligand between two transition-metal centers; using Cp2Ti(NSO)2, we describe bi- and tetrametallic systems.
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Affiliation(s)
- Liam J R McGeachie
- EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, United Kingdom
| | - Michael Bühl
- EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, United Kingdom
| | - David B Cordes
- EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, United Kingdom
| | - Alexandra M Z Slawin
- EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, United Kingdom
| | - J Derek Woollins
- EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, United Kingdom.,Department of Chemistry, Khalifa University, Abu Dhabi, United Arab Emirates
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13
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Lv ZJ, Chai Z, Zhu M, Wei J, Zhang WX. Selective Coupling of Lanthanide Metallacyclopropenes and Nitriles via Azametallacyclopentadiene and η 2-Pyrimidine Metallacycle. J Am Chem Soc 2021; 143:9151-9161. [PMID: 34029479 DOI: 10.1021/jacs.1c03604] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Exploring new lanthanide metallacycles and finding their unique chemistry different from the analogues of transition metals are of great interest and importance. In this work, we reported the synthesis, characterization, and reactivity toward nitriles of two lanthanide metallacyclopropenes: lutetacyclopropene 2a and dysprosacyclopropene 2b. The selective coupling of 2a and three molecules of PhCN was found for the first time to provide the unexpected fused lutetacycle 3a with one 1,6-dihydropyrimidine ring. Mechanistic studies by DFT calculations reveal that the triple insertion of PhCN into 2a proceeds through four key steps: the insertion of the first PhCN into 2a giving azalutetacyclopentadiene IM1, the insertion of the second PhCN into the Lu-N bond of IM1, the intramolecular electrocyclization providing a highly strained η2-pyrimidine metallacycle, and the insertion of the third PhCN into the Lu-Csp3 bond. Isolation and characterization of two active intermediates, azalutetacyclopentadiene IM1 and η2-pyrimidine dysprosacycle, provide critical evidence for the formation of 3a. Furthermore, IM1 was also reported to react with TMSCN, isocyanides, or W(CO)6 to furnish the fused [4,5] lutetacycles. The chemistry of two lanthanide metallacyclopropenes with nitriles is significantly different from these metallacyclopropenes of scandium and other metals. Most notably, the azalutetacyclopentadienes, η2-pyrimidine complex, and other metallacycles all represent the first examples in rare-earth organometallic chemistry; the formation of these new lutetacycles provides concrete evidence for understanding the mechanism of transition metal promoted or catalyzed [2+2+2] cycloaddition between alkynes and nitriles.
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Affiliation(s)
- Ze-Jie Lv
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhengqi Chai
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Miaomiao Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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14
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Wang D, Ding W, Hou G, Zi G, Walter MD. Uranium versus Thorium: Synthesis and Reactivity of [η 5 -1,2,4-(Me 3 C) 3 C 5 H 2 ] 2 U[η 2 -C 2 Ph 2 ]. Chemistry 2021; 27:6767-6782. [PMID: 33559922 PMCID: PMC8251885 DOI: 10.1002/chem.202100089] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Indexed: 01/09/2023]
Abstract
The synthesis, electronic structure, and reactivity of a uranium metallacyclopropene were comprehensively studied. Addition of diphenylacetylene (PhC≡CPh) to the uranium phosphinidene metallocene [η5‐1,2,4‐(Me3C)3C5H2]2U=P‐2,4,6‐tBu3C6H2 (1) yields the stable uranium metallacyclopropene, [η5‐1,2,4‐(Me3C)3C5H2]2U[η2‐C2Ph2] (2). Based on density functional theory (DFT) results the 5f orbital contributions to the bonding within the metallacyclopropene U‐(η2‐C=C) moiety increases significantly compared to the related ThIV compound [η5‐1,2,4‐(Me3C)3C5H2]2Th[η2‐C2Ph2], which also results in more covalent bonds between the [η5‐1,2,4‐(Me3C)3C5H2]2U2+ and [η2‐C2Ph2]2− fragments. Although the thorium and uranium complexes are structurally closely related, different reaction patterns are therefore observed. For example, 2 reacts as a masked synthon for the low‐valent uranium(II) metallocene [η5‐1,2,4‐(Me3C)3C5H2]2UII when reacted with Ph2E2 (E=S, Se), alkynes and a variety of hetero‐unsaturated molecules such as imines, ketazine, bipy, nitriles, organic azides, and azo derivatives. In contrast, five‐membered metallaheterocycles are accessible when 2 is treated with isothiocyanate, aldehydes, and ketones.
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Affiliation(s)
- Deqiang Wang
- Department of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Wanjian Ding
- Department of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Guohua Hou
- Department of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Guofu Zi
- Department of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Marc D Walter
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
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15
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Fischer M, Reiß F, Hering-Junghans C. Titanocene pnictinidene complexes. Chem Commun (Camb) 2021; 57:5626-5629. [PMID: 33989372 DOI: 10.1039/d1cc01305j] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The phospha-Wittig reagent MesTerPPMe3 (MesTer = 2,6-{2,4,6-Me3-C6H2}-C6H3) and arsa-Wittig reagent DipTerAsPMe3 (DipTer = 2,6-{2,6-iPr2-C6H3}-C6H3) have been employed to synthesize the titanocene complexes Cp2Ti(PMe3)PnAr (Pn = P, As) with terminal phosphinidene or arsinidene ligands, respectively. Ab initio studies show that the description as singlet biradicaloids in their ground state is warranted.
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Affiliation(s)
- Malte Fischer
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, Rostock 18059, Germany.
| | - Fabian Reiß
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, Rostock 18059, Germany.
| | - Christian Hering-Junghans
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, Rostock 18059, Germany.
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16
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Reinholdt A, Pividori D, Laughlin AL, DiMucci IM, MacMillan SN, Jafari MG, Gau MR, Carroll PJ, Krzystek J, Ozarowski A, Telser J, Lancaster KM, Meyer K, Mindiola DJ. A Mononuclear and High-Spin Tetrahedral Ti II Complex. Inorg Chem 2020; 59:17834-17850. [PMID: 33258366 PMCID: PMC7928263 DOI: 10.1021/acs.inorgchem.0c02586] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Indexed: 12/31/2022]
Abstract
A high-spin, mononuclear TiII complex, [(TptBu,Me)TiCl] [TptBu,Me- = hydridotris(3-tert-butyl-5-methylpyrazol-1-yl)borate], confined to a tetrahedral ligand-field environment, has been prepared by reduction of the precursor [(TptBu,Me)TiCl2] with KC8. Complex [(TptBu,Me)TiCl] has a 3A2 ground state (assuming C3v symmetry based on structural studies), established via a combination of high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy, solution and solid-state magnetic studies, Ti K-edge X-ray absorption spectroscopy (XAS), and both density functional theory and ab initio (complete-active-space self-consistent-field, CASSCF) calculations. The formally and physically defined TiII complex readily binds tetrahydrofuran (THF) to form the paramagnetic adduct [(TptBu,Me)TiCl(THF)], which is impervious to N2 binding. However, in the absence of THF, the TiII complex captures N2 to produce the diamagnetic complex [(TptBu,Me)TiCl]2(η1,η1;μ2-N2), with a linear Ti═N═N═Ti topology, established by single-crystal X-ray diffraction. The N2 complex was characterized using XAS as well as IR and Raman spectroscopies, thus establishing this complex to possess two TiIII centers covalently bridged by an N22- unit. A π acid such as CNAd (Ad = 1-adamantyl) coordinates to [(TptBu,Me)TiCl] without inducing spin pairing of the d electrons, thereby forming a unique high-spin and five-coordinate TiII complex, namely, [(TptBu,Me)TiCl(CNAd)]. The reducing power of the coordinatively unsaturated TiII-containing [(ΤptBu,Me)TiCl] species, quantified by electrochemistry, provides access to a family of mononuclear TiIV complexes of the type [(TptBu,Me)Ti═E(Cl)] (with E2- = NSiMe3, N2CPh2, O, and NH) by virtue of atom- or group-transfer reactions using various small molecules such as N3SiMe3, N2CPh2, N2O, and the bicyclic amine 2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene.
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Affiliation(s)
- Anders Reinholdt
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Daniel Pividori
- Inorganic
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University (FAU) Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Alexander L. Laughlin
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Ida M. DiMucci
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N. MacMillan
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Mehrafshan G. Jafari
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Michael R. Gau
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J. Carroll
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - J. Krzystek
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Andrew Ozarowski
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Joshua Telser
- Department
of Biological, Physical and Health Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Kyle M. Lancaster
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Karsten Meyer
- Inorganic
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University (FAU) Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Daniel J. Mindiola
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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17
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Zhang Y, Wu B, Zhong M, Zhang WX, Xi Z. Cyclic Bis-alkylidene Complexes of Titanium and Zirconium: Synthesis, Characterization, and Reaction. Chemistry 2020; 26:16472-16479. [PMID: 32875626 DOI: 10.1002/chem.202003240] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/29/2020] [Indexed: 11/06/2022]
Abstract
Transition-metal alkylidenes have exhibited wide applications in organometallic chemistry and synthetic organic chemistry, however, cyclic Schrock-carbene-like bis-alkylidenes of group 4 metals with a four-electron donor from an alkylidene have not been reported. Herein, the synthesis and characterization of five-membered cyclic bis-alkylidenes of titanium (4 a,b) and zirconium (5 a,b) are reported, as the first well-defined group 4 metallacyclopentatrienes, by two-electron reduction of their corresponding titana- and zirconacyclopentadienes. DFT analyses of 4 a show a four-electron donor (σ-donation and π-donation) from an alkylidene carbon to the metal center. The reaction of 4 a with N,N'-diisopropylcarbodiimide (DIC) leads to the [2+2]-cycloaddition product 6. Compound 4 a reacted with CO, affording the oxycyclopentadienyl titanium complex 7. These reactivities demonstrate the multiple metal-carbon bond character. The reactions of 4 a or 5 a with cyclooctatetraene (COT) or azobenzene afforded sandwich titanium complex 8 or diphenylhydrazine-coordinated zirconacyclopentadiene 9, respectively, which exhibit two-electron reductive ability.
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Affiliation(s)
- Yongliang Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Botao Wu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Mingdong Zhong
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P.R. China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Shanghai, 200032, P.R. China
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18
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Rosenthal U. Update for Reactions of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes: A Never-Ending Story? Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00622] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- U. Rosenthal
- Leibniz Institute for Catalysis at the University of Rostock, Albert-Einstein-Straße 29A, 18059 Rostock, Germany
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19
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Fischer M, Wolff MC, del Horno E, Schmidtmann M, Beckhaus R. Synthesis, Reactivity, and Insights into the Lewis Acidity of Mononuclear Titanocene Imido Complexes Bearing Sterically Demanding Terphenyl Moieties. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00452] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Malte Fischer
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, D-18059 Rostock, Germany
| | - Marie Christin Wolff
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Estefanía del Horno
- Departamento de Química Orgánica y Química Inorgánica, Universidad de Alcalá, 28805 Alcalá de Henares-Madrid, Spain
| | - Marc Schmidtmann
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Rüdiger Beckhaus
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
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Ghosh B, Phukan AK. Probing the potential of metalla-N-heterocyclic carbenes towards activation of enthalpically strong bonds. Dalton Trans 2020; 49:9505-9515. [PMID: 32608419 DOI: 10.1039/d0dt01363c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Density functional theory calculations are employed to explore the reactivity of metalla-N-heterocyclic carbenes (MNHCs) towards activation of a variety of small molecules (H2, NH3, PH3, SiH3Ph and CH4). All the MNHCs considered are found to have a stable singlet ground state and possess suitable electronic properties for their application in small molecule activation. The calculated energy barriers of E-H (E = H, C, N, Si, P) activation for the MNHCs are found to be in agreement with those of the experimentally evaluated cyclic alkyl(amino)carbene (CAAC) and diamidocarbenes (DACs), thereby indicating the activating effect of the incorporation of an ancillary metal center within a cyclic NHC, and highlighting a new, underexplored strategy in achieving difficult bond activations with carbenes.
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Affiliation(s)
- Bijoy Ghosh
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India.
| | - Ashwini K Phukan
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India.
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