Bimetallic Hydroformylation Catalysis: In Situ Characterization of a Dinuclear Rhodium(II) Dihydrido Complex with the Largest Rh-HNMR Coupling Constant

摘要

The ability of two or more metal centers to cooperate in heterogeneous catalytic reactions is quite common and well established. Bi- or polymetallic cooperativity in homogeneous catalysis, however, is much rarer and far less well understood. Perhapsthe most dramatic example of bimetallic cooperativity in homogeneous catalysis is the homobimetallic rhodium complex rac-[Rh_2(nbd)_2(et, ph-P4)](BF_4)_2 1 (nbd = norbornadiene; et,ph-P4 = (Et_2PCH_2CH_2)P(Ph)CH_2P(Ph)CH_2CH_2PEt_2), which is a precursorfor a highly active and regioselective catalyst for the hydroformylation of 1-alkenes.