A bimetallic hydroformylation catalyst: high regioselectivity and reactivity through homobimetallic cooperativity.

Broussard, M E; Juma, B; Train, S G; Peng, W J; Laneman, S A; Stanley, G G · Science · 1993

basic_science · Level V

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Abstract

The racemic and meso diastereomers of an electron-rich binucleating tetraphosphine ligand have been used to prepare homobimetallic rhodium norbornadiene complexes. The racemic bimetallic Rh complex is an excellent hydroformylation catalyst for 1-alkenes, giving both a high rate of reaction and high regioselectivity for linear aldehydes, whereas the meso complex is considerably slower and less selective. A mechanism involving bimetallic cooperativity between the two rhodium centers in the form of an intramolecular hydride transfer is proposed. Mono- and bimetallic model complexes in which the possibility for bimetallic cooperativity has been reduced or eliminated are very poor catalysts.