A bimetallic hydroformylation catalyst: high regioselectivity and reactivity through homobimetallic cooperativity.
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.
Broussard
M E
ME
Juma
B
B
Train
S G
SG
Peng
W J
WJ
Laneman
S A
SA
Stanley
G G
GG