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Kinzel NW, Demirbas D, Bill E, Weyhermüller T, Werlé C, Kaeffer N, Leitner W. Systematic Variation of 3d Metal Centers in a Redox-Innocent Ligand Environment: Structures, Electrochemical Properties, and Carbon Dioxide Activation. Inorg Chem 2021; 60:19062-19078. [PMID: 34851088 PMCID: PMC8693193 DOI: 10.1021/acs.inorgchem.1c02909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Coordination compounds
of earth-abundant 3d transition metals are
among the most effective catalysts for the electrochemical reduction
of carbon dioxide (CO2). While the properties of the metal
center are crucial for the ability of the complexes to electrochemically
activate CO2, systematic variations of the metal within
an identical, redox-innocent ligand backbone remain insufficiently
investigated. Here, we report on the synthesis, structural and spectroscopic
characterization, and electrochemical investigation of a series of
3d transition-metal complexes [M = Mn(I), Fe(II), Co(II), Ni(II),
Cu(I), and Zn(II)] coordinated by a new redox-innocent PNP pincer
ligand system. Only the Fe, Co, and Ni complexes reveal distinct metal-centered
electrochemical reductions from M(II) down to M(0) and show indications
for interaction with CO2 in their reduced states. The Ni(0)
d10 species associates with CO2 to form a putative
Aresta-type Ni-η2-CO2 complex, where electron
transfer to CO2 through back-bonding is insufficient to
enable electrocatalytic activity. By contrast, the Co(0) d9 intermediate binding CO2 can undergo additional electron
uptake into a formal cobalt(I) metallacarboxylate complex able to
promote turnover. Our data, together with the few literature precedents,
single out that an unsaturated coordination sphere (coordination number
= 4 or 5) and a d7-to-d9 configuration in the
reduced low oxidation state (+I or 0) are characteristics that foster
electrochemical CO2 activation for complexes based on redox-innocent
ligands. A series of 3d transition-metal complexes
(M = Mn, Fe, Co,
Ni, Cu, and Zn) coordinated by a new redox-innocent PNP pincer ligand
system were synthesized and structurally as well as electrochemically
analyzed to illuminate the role of the metal center in molecular electrochemical
carbon dioxide (CO2) activation.
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Affiliation(s)
- Niklas W Kinzel
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany.,Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074 Aachen, Germany
| | - Derya Demirbas
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Thomas Weyhermüller
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Christophe Werlé
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany.,Ruhr University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
| | - Nicolas Kaeffer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Walter Leitner
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany.,Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074 Aachen, Germany
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2
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Controlling the Lifetime of the Triplet MLCT State in Fe(II) Polypyridyl Complexes through Ligand Modification. INORGANICS 2020. [DOI: 10.3390/inorganics8020016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A computational study is presented in which two strategies of ligand modifications have been explored to invert the relative energy of the metal-to-ligand charge transfer (MLCT) and metal-centered (MC) state in Fe(II)-polypyridyl complexes. Replacing the bipyridines by stronger σ donors increases the ligand-field strength and pushes the MC state to higher energy, while the use of ligands with a larger π conjugation leads to lower MLCT energies.
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3
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Can Immobilization of an Inactive Iron Species Switch on Catalytic Activity in the Suzuki Reaction? Catal Letters 2019. [DOI: 10.1007/s10562-019-02978-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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4
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Devillard M, Ehlers A, Siegler MA, van der Vlugt JI. Selective Carbanion-Pyridine Coordination of a Reactive P,N Ligand to Rh I. Chemistry 2019; 25:3875-3883. [PMID: 30600857 PMCID: PMC6519283 DOI: 10.1002/chem.201805504] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/12/2018] [Indexed: 01/12/2023]
Abstract
Ligands with reactive carbon sites in the periphery of a metal center have emerged as a powerful approach for metal-ligand bond activation. These reactive carbon sites are commonly generated by deprotonation strategies. Carbon-silicon bond cleavage is a potential alternative to access such constructs. Herein, the monodesilylation of bis-silyl-substituted P,N scaffold PNSi2 in the coordination sphere of [RhI (Cl)(CO)(PNSi2 )] (1) with sodium azide is disclosed. This affords a unique dinucleating anionic κ2 -C,N-κ1 -P ligand with a carbanionic methine carbon atom directly bound to rhodium as part of a four-membered Rh-N-C-C rhodacycle. This dimer undergoes meta-pyridine C-H activation facilitated by weak bases, which leads to a desymmetrization of the system and provides a σ,π-bridging 3-pyridyl fragment bound to RhI . The facile Si-C cleavage strategy may pave the way to studying the reactivity and functionalization of a variety of κ2 -C,N-coordinated pyridine scaffolds for selective transformations.
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Affiliation(s)
- Marc Devillard
- van ‘t Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
| | - Andreas Ehlers
- van ‘t Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
- Department of ChemistryUniversity of Johannesburg, P.O. Box 254Auckland ParkJohannesburgSouth Africa
| | - Maxime A. Siegler
- Department of ChemistryJohns Hopkins University3400 N Charles StreetBaltimoreMD21218USA
| | - Jarl Ivar van der Vlugt
- van ‘t Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
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5
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Rotter M, Mastalir M, Glatz M, Stöger B, Kirchner K. Crystal structure of the tetra-hydro-furan disolvate of a 94:6 solid solution of [ N2, N6-bis-(di- tert-butyl-phosphan-yl)pyridine-2,6-di-amine]-dibromido-manganese(II) and its monophosphine oxide analogue. Acta Crystallogr E Crystallogr Commun 2017; 73:1308-1311. [PMID: 28932462 PMCID: PMC5588568 DOI: 10.1107/s2056989017011276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 07/31/2017] [Indexed: 11/29/2022]
Abstract
The MnBr2 complex of N2,N6-bis-(di-tert-butyl-phosphan-yl)pyridine-2,6-di-amine (1·MnBr2) co-crystallizes with 5.69% of the monophosphine oxide analogue (1O·MnBr2) and two tetra-hydro-furan (THF) mol-ecules, namely [N2,N6-bis-(di-tert-butyl-phosphan-yl)pyridine-2,6-di-amine]-dibromido-manganese(II)-[bis-(di-tert-butyl-phosphan-yl)({6-[(di-tert-butyl-phosphan-yl)amino]-pyridin-2-yl}amino)-phosphine oxide]di-bromido-manganese(II)-tetra-hydro-furan (0.94/0.06/2), [MnBr2(C21H41N3P2)]0.94[MnBr2(C21H41N3OP2)]0.06·2C4H8O. The 1·MnBr2 and 1O·MnBr2 complexes are occupationally disordered about general positions. Both complexes feature square-pyramidal coordination of the MnII atoms. They are connected by weak N-H⋯Br hydrogen bonding into chains extending along [001]. The THF mol-ecules are located between the layers formed by these chains. One THF mol-ecule is involved in hydrogen bonding to an amine H atom.
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Affiliation(s)
- Markus Rotter
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, A-1060 Vienna, Austria
| | - Matthias Mastalir
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, A-1060 Vienna, Austria
| | - Mathias Glatz
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, A-1060 Vienna, Austria
| | - Berthold Stöger
- X-Ray Centre, TU Wien, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Karl Kirchner
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, A-1060 Vienna, Austria
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6
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Synthesis, characterization and reactivity of vanadium, chromium, and manganese PNP pincer complexes. Inorganica Chim Acta 2017. [DOI: 10.1016/j.ica.2016.02.064] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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7
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Schröder-Holzhacker C, Gorgas N, Stöger B, Kirchner K. Synthesis and reactivity of BINEPINE-based chiral Fe(II) PNP pincer complexes. MONATSHEFTE FUR CHEMIE 2016; 147:1023-1030. [PMID: 27340297 PMCID: PMC4869728 DOI: 10.1007/s00706-016-1706-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/11/2016] [Indexed: 11/25/2022]
Abstract
ABSTRACT A new asymmetric chiral PNP ligand based on the 2,6-diaminopyridine scaffold featuring a R-BINEPINE moiety was prepared. Treatment of anhydrous FeX2 (X = Cl, Br) with 1 equiv of PNP-iPr,BIN at room temperature afforded the coordinatively unsaturated paramagnetic complexes [Fe(PNP-iPr,BIN)X2]. The structure of [Fe(PNP-iPr,BIN)Cl2] is described. Both complexes react readily with the strong π-acceptor ligand CO in solution to afford selectively the diamagnetic complexes trans-[Fe(PNP-iPr,BIN)(CO)X2] in quantitative yield. Due the lability of the CO ligand, these complexes are only stable under a CO atmosphere and isolation in pure form was not possible. The preparation of the carbonyl hydride complex [Fe(PNP-iPr,BIN)(H)(CO)Br] was achieved albeit in low yields via a one pot procedure by treatment of [Fe(PNP-iPr,BINEP)Br2] with CO and subsequent reaction with Na[HBEt3]. This complex was obtained as an inseparable mixture of two diastereomers in a ca. 1:1 ratio and was tested as catalyst for the hydrogenation of ketones. The catalyst showed acceptable activity under mild conditions (5 bar H2, room temperature) with yields up to >99 % within 18 h. GRAPHICAL ABSTRACT
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Affiliation(s)
- Christian Schröder-Holzhacker
- />Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, 1060 Vienna, Austria
| | - Nikolaus Gorgas
- />Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, 1060 Vienna, Austria
| | - Berthold Stöger
- />Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
| | - Karl Kirchner
- />Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, 1060 Vienna, Austria
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8
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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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9
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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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10
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Mastalir M, Rosenberg EE, Kirchner K. A practical synthesis of substituted 2,6-diaminopyridines via microwave-assisted copper-catalyzed amination of halopyridines. Tetrahedron 2015. [DOI: 10.1016/j.tet.2015.08.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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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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12
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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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Tang Z, Otten E, Reek JNH, van der Vlugt JI, de Bruin B. Dynamic Ligand Reactivity in a Rhodium Pincer Complex. Chemistry 2015. [DOI: 10.1002/chem.201501453] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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