Chelate bite effects for [Pd(triphosphine)(solvent)](BF{sub 4}){sub 2} complexes in electrochemical CO{sub 2} reduction and the heterolytic cleavage of molecular hydrogen
- National Renewable Energy Lab., Golden, CO (United States)
- Univ. of Colorado, Boulder, CO (United States)
A series of [Pd(triphosphine)(CH{sub 3}CN)](BF{sub 4}){sub 2} complexes has been prepared with different chelate bites. Stoichiometric reactions of these complexes with triethlyphosphine, NaBH{sub 4}, and H{sub 2} have been studied, as well as the catalytic electrochemical reduction of CO{sub 2}. All of these reactions show significant chelate effects. [Pd(ttpE)(CH{sub 3}CN)](BF{sub 4}){sub 2} (where ttpE is bis(3-(diethylphosphino)propyl)phenylphosphine) catalyzes the electrochemical reduction of CO{sub 2} to CO in acidic dimethylformamide solutions and reacts with NaBH{sub 4} or H{sub 2} to form [Pd(ttpE)(H)](BF{sub 4}). The latter complex is the decomposition product formed under catalytic conditions. X-ray diffraction studies of [Pd(ttpE)(CH{sub 3}CN)](BF{sub 4}){sub 2} and [Pd(ttpE)(H)](BF{sub 4}) provide insight into possible steric origins of reactivity differences between the last two complexes and analogous complexes with smaller chelate bites. [Pd(ttpE)(CH{sub 3}CN)](BF{sub 4}){sub 2} has square-planar structure with one methylene group of the ethyl substituents making a close contact with the nitrogen atom of acetonitrile. This steric interaction likely contributes to some of the reactivity differences observed. [Pd(ttpE)(H)](BF{sub 4}) also has a square-planar structure with the two terminal phosphorus atoms of the triphosphine ligand distorted slightly toward the hydride ligand. 38 refs., 8 figs., 4 tabs.
- OSTI ID:
- 380807
- Journal Information:
- Organometallics, Vol. 15, Issue 15; Other Information: PBD: 23 Jul 1996
- Country of Publication:
- United States
- Language:
- English
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