Homogeneous Catalysis VI. Hydrosilylation Using Tri(Pentanedionato)Rhodium(III) or Tetrakis(µ-Acetato)Dirhodium(II) as Catalysts

The catalytic activity of tris(pentanedionato)rhodium(III), (or rhodium(III) acetylacetonate) (I) has been investigated for the hydrosilylation of a variety of organic substrates: alkenes, terminal or internal acetylenes, conjugated dienes, or a,ß-unsaturated carbonyls or nitriles. With PhCH=CH2 or PhCH2CH=CH2, ?-substitution was unexpectedly observed, as well as addition. Compound I is an active hydrosilylation catalyst in the absence of any added reducing agent, as is tetrakis(µ-acetato)dirhodium(II) (II) which does not, however, show any unusual catalytic activity due to the two metal atom cluster. Possible mechanisms are suggested