3
|
Baya M, Houghton J, Konya D, Champouret Y, Daran JC, Almeida Leñero KQ, Schoon L, Mul WP, Oort ABV, Meijboom N, Drent E, Orpen AG, Poli R. Pd(I) Phosphine Carbonyl and Hydride Complexes Implicated in the Palladium-Catalyzed Oxo Process. J Am Chem Soc 2008; 130:10612-24. [DOI: 10.1021/ja8012903] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Miguel Baya
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Jennifer Houghton
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Denes Konya
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Yohan Champouret
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Jean-Claude Daran
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Karina Q. Almeida Leñero
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Lodewijk Schoon
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Wilhelmus P. Mul
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - A. Bart van Oort
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Nicolaas Meijboom
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Eite Drent
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - A. Guy Orpen
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| | - Rinaldo Poli
- Laboratoire de Chimie de Coordination, UPR CNRS 8241 liée par convention à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 Route de Narbonne, 31077 Toulouse Cedex, France, Shell Global Solutions International B.V. Amsterdam, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, and School of Chemistry, University of Bristol, Cantock’s Close, Bristol, U.K. BS8 1TS
| |
Collapse
|
6
|
Cugnet C, Lucas D, Collange E, Hanquet B, Vallat A, Mugnier Y, Soldera A, Harvey PD. Generation, Characterization, and Electrochemical Behavior of the Palladium–Hydride Cluster [Pd3(dppm)3(μ3-CO)(μ3-H)]+ (dppm=Bis(diphenylphosphinomethane). Chemistry 2007; 13:5338-46. [PMID: 17455171 DOI: 10.1002/chem.200700069] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Addition of formate on the dicationic cluster [Pd(3)(dppm)(3)(mu(3)-CO)](2+) (dppm=bis(diphenylphosphinomethane) affords quantitatively the hydride cluster [Pd(3)(dppm)(3)(mu(3)-CO)(mu(3)-H)](+). This new palladium-hydride cluster has been characterised by (1)H NMR, (31)P NMR and UV/Vis spectroscopy and MALDI-TOF mass spectrometry. The unambiguous identification of the capping hydride was made from (2)H NMR spectroscopy by using DCO(2) (-) as starting material. The mechanism of the hydride complex formation was investigated by UV/Vis stopped-flow methods. The kinetic data are consistent with a two-step process involving: 1) host-guest interactions between HCO(2) (-) and [Pd(3)(dppm)(3)(mu(3)-CO)](2+) and 2) a reductive elimination of CO(2). Two alternatives routes to the hydride complex were also examined : 1) hydride transfer from NaBH(4) to [Pd(3)(dppm)(3)(mu(3)-CO)](2+) and 2) electrochemical reduction of [Pd(3)(dppm)(3)(mu(3)-CO)](2+) to [Pd(3)(dppm)(3)(mu(3)-CO)](0) followed by an addition of one equivalent of H(+). Based on cyclic voltammetry, evidence for a dual mechanism (ECE and EEC; E=electrochemical (one-electron transfer), C=chemical (hydride dissociation)) for the two-electron reduction of [Pd(3)(dppm)(3)(mu(3)-CO)(mu(3)-H)](+) to [Pd(3)(dppm)(3)(mu(3)-CO)](0) is provided, corroborated by digital simulation of the experimental results. Geometry optimisations of the [Pd(3)(H(2)PCH(2)PH(2))(3)(mu(3)-CO)(mu(3)-H)](n) model clusters were performed by using DFT at the B3 LYP level. Upon one-electron reductions, the Pd--Pd distance increases from a formal single bond (n=+1), to partially bonding (n=0), to weak metal-metal interactions (n=-1), while the Pd--H bond length remains relatively the same.
Collapse
Affiliation(s)
- Cyril Cugnet
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Cugnet C, Mugnier Y, Dal Molin S, Brevet D, Lucas D, Harvey PD. Thermal and Electrochemically Assisted Pd−Cl Bond Cleavage in the d9−d9 Pd2(dppm)2Cl2 Complex by Pd3(dppm)3(CO)n+ Clusters (n = 2, 1, 0). Inorg Chem 2007; 46:3083-8. [PMID: 17371010 DOI: 10.1021/ic061777h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new aspect of reactivity of the cluster [Pd3(dppm)3(micro3-CO)]n+, ([Pd3]n+, n = 2, 1, 0) with the low-valent metal-metal-bonded Pd2(dppm)2Cl2 dimer (Pd2Cl2) was observed using electrochemical techniques. The direct reaction between [Pd3]2+ and Pd2Cl2 in THF at room temperature leads to the known [Pd3(dppm)3(micro3-CO)(Cl)]+ ([Pd3(Cl)]+) adduct and the monocationic species Pd2(dppm)2Cl+ (very likely as Pd2(dppm)2(Cl)(THF)+, [Pd2Cl]+) as unambiguously demonstrated by UV-vis and 31P NMR spectroscopy. In this case, [Pd3]2+ acts as a strong Lewis acid toward the labile Cl- ion, which weakly dissociates from Pd2Cl2 (i.e., dissociative mechanism). Host-guest interactions between [Pd3]2+ and Pd2Cl2 seem unlikely on the basis of computer modeling because of the strong screening of the Pd-Cl fragment by the Ph-dppm groups in Pd2Cl2. The electrogenerated clusters [Pd3]+ and [Pd3]0 also react with Pd2Cl2 to unexpectedly form the same oxidized adduct, [Pd3(Cl)]+, despite the known very low affinity of [Pd3]+ and [Pd3]0 toward Cl- ions. The reduced biproduct in this case is the highly reactive zerovalent species "Pd2(dppm)2" or "Pd(dppm)" as demonstrated by quenching with CDCl3 (forming the well-known complex Pd(dppm)Cl2) or in presence of dppm (forming the known Pd2(dppm)3 d10-d10 dimer). To bring these halide-electron exchange reactions to completion for [Pd3]+ and [Pd3]0, 0.5 and 1.0 equiv of Pd2Cl2 are necessary, respectively, accounting perfectly for the number of exchanged electrons. The presence of a partial dissociation of Pd2Cl2 into the Cl- ion and the monocation [Pd2Cl]+, which is easier to reduce than Pd2Cl2, is suggested to explain the overall electrochemical results. It is possible to regulate the nature of the species formed from Pd2Cl2 by changing the state of charge of the title cluster.
Collapse
Affiliation(s)
- Cyril Cugnet
- Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR CNRS 5260, Université de Bourgogne, Faculté des Sciences Mirande, Dijon, France
| | | | | | | | | | | |
Collapse
|
8
|
Cugnet C, Lucas D, Lemaître F, Collange E, Soldera A, Mugnier Y, Harvey PD. Unexpected reaction of the unsaturated cluster host and catalyst [Pd3(mu3-CO)(dppm)3]2+ with the hydroxide ion: spectroscopic and kinetic evidence of an inner-sphere mechanism. Chemistry 2006; 12:8386-95. [PMID: 16897803 DOI: 10.1002/chem.200600395] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The title cluster, [Pd(3)(mu(3)-CO)(dppm)(3)](2+) (dppm=bis(diphenylphosphino)methane), reacts with one equivalent of hydroxide anions (OH(-)), from tetrabutylammonium hydroxide (Bu(4)NOH), to give the paramagnetic [Pd(3)(mu(3)-CO)(dppm)(3)](+) species. Reaction with another equivalent of OH(-) leads to the zero-valent compound [Pd(3)(mu(3)-CO)(dppm)(3)](0). From electron paramagnetic resonance analysis of the reaction medium using the spin-trap agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the 2-tetrahydrofuryl or methyl radicals, deriving from the tetrahydrofuran (THF) or dimethyl sulfoxide (DMSO) solvent, respectively, were detected. For both [Pd(3)(mu(3)-CO)(dppm)(3)](2+) and [Pd(3)(mu(3)-CO)(dppm)(3)](+), the mechanism involves, in a first equilibrated step, the formation of a hydroxide adduct, [Pd(3)(mu(3)-CO)(dppm)(3)(OH)]((n-1)+) (n=1, 2), which reacts irreversibly with the solvent. The kinetics were resolved by means of stopped-flow experiments and are consistent with the proposed mechanism. In the presence of an excess of Bu(4)NOH, an electrocatalytic process was observed with modest turnover numbers (7-8). The hydroxide adducts [Pd(3)(mu(3)-CO)(dppm)(3)(OH)]((n-1)+) (n=1, 2), which bear important similarities to the well-known corresponding halide adducts [Pd(3)(mu(3)-CO)(dppm)(3)(mu(3)-X)](n) (X=Cl, Br, I), have been studied by using density functional theory (DFT). Although the optimised geometry for the cluster in its +2 and 0 oxidation states (i.e., cation and anion clusters, respectively) is the anticipated mu(3)-OH form, the paramagnetic species, [Pd(3)(mu(3)-CO)(dppm)(3)(OH)](0), shows a mu(2)-OH form; this suggests an important difference in electronic structure between these three species.
Collapse
Affiliation(s)
- Cyril Cugnet
- Université de Bourgogne, Laboratoire de Synthèse et Electrosynthèse Organométalliques, CNRS UMR 5188, Faculté des Sciences Mirande, 9 Avenue Alain Savary, 21000 Dijon, France
| | | | | | | | | | | | | |
Collapse
|