Cobalt−Alkyne Complexes with Diphosphine Ligands as Mechanistic Probes for the Pauson−Khand Reaction

Autor:	Volker Derdau, Ina Dix, Peter G. Jones, Sabine Laschat
Rok vydání:	1999
Předmět:	chemistry.chemical_classification Ligand Pauson–Khand reaction Organic Chemistry Diastereomer Alkyne Medicinal chemistry Inorganic Chemistry chemistry.chemical_compound chemistry Phenylacetylene Physical and Theoretical Chemistry Phosphine Norbornene BINAP
Zdroj:	Organometallics. 18:3859-3864
ISSN:	1520-6041 0276-7333
Popis:	Enantiomerically pure (3,3-dimethylbutyne)[(R)-BINAP]Co2(CO)4 (6a) was obtained via thermal ligand exchange in 27% yield as a single diastereomer. X-ray crystal structure analysis of 6a revealed a basal bridged coordination of the BINAP ligand and a distorted geometry of the central Co2C2 core. Comparison of 6a with the structurally related (phenylacetylene)dppm)Co2(CO)4 (7) revealed that the geometric distortion is mainly caused by the BINAP ligand. Due to the replacement of basal CO ligands anti to the tert-butyl group in 6a by the diphosphine, the Pauson−Khand reaction of 6a with norbornene is completely suppressed. Comparison with (3,3-dimethylbutyne)(dppm)Co2(CO)4 (6b), (3,3-dimethylbutyne)(dppe)Co2(CO)4 (6c), 7, (3,3-dimethylbutyne)Co2(CO)6 (8a), and (3,3-dimethylbutyne)(PPh3)Co2(CO)5 (8b) showed a retardation of the reaction rate caused by phosphines. The mechanistic consequences for the Pauson−Khand reaction employing chiral phosphine ligands are discussed.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::695d6df429c544c8a891b284c5a0316a https://doi.org/10.1021/om990311m Zobrazit plný text záznamu