RHODIUM(I) COMPLEXES OF BETA-DIKETONATES AND RELATED LIGANDS AS HOMOGENEOUS HYDROGENATION CATALYSTS

Rhodium(I) complexes of beta-diketonates such as bis(eta-2-ethene)[1,3-(1-phenyl)-butanedionato-O,O']rhodium(I) and related (O ... O) ligands are active catalysts for the hydrogenation of unhindered alkenes at 30-degrees-C (1 atm H-2). Substrates such as alpha-acylaminocinnamic acid are not hydrogenated under these conditions, a result that can be used as a test for homogeneity in these catalytic systems. The crystal structures of two catalysts are described: bis(eta-2 -ethene)[1,3-(1-ferrocenyl)-butanedionato-O,O'] rhodium(I), orthorhombic, space group P2(1)2(1)2(1), with a = 7.8550(4), b = 9.8400(4), c = 21.5093(7) angstrom, and Z = 4. R = 0.037 and R(w) = 0.042 for 2993 reflections with I > 3-sigma(I). (1,5-cyclooctadiene)(2'-acetylphenoxy-O,O')rhodium(I), triclinic, space group P1BAR with a = 7.6634(5), b = 9.7831(3), c = 10.1112(6) angstrom, alpha = 104.763(3), beta = 73.668(6), gamma = 98.470(4)degrees, and Z = 2.R = 0.028 and R(W) = O.034 for 5174 reflections with I > 3-sigma(I).