Dinuclear rhodium(1) complexes for the selective hydroformylation of alkenes using either CO/H2 or CO/H20

The dinuclear rhodium(1) R ~ ~ ( P S R ) ~ ( C O ) ~ L ~ complexes have been designed for the low pressure hydroformylation of vario s alkenes. The reaction is fully selective in aldehydes and turnover frequencies as high as 1 s ~ can be reached. A catalytic cycle in which all the intermediates remain dinuclear is consistent with the observed data and involves a cooperative effect between the two metal centres. The use of the water-soluble tris(m-sulphopheny1)phosphine ligand led to 96% of selectivity in linear aldehyde and solved very easily the problem of catalyst recovery by decantation ; in this case the C o r n 2 0 and CO/H2 couples can be undistinguishably used as feedstock.