Synthesis of novel ruthenium complexes of 2,2′-bis(diphenylphosphinomethyl)-1,1′-biphenyl and their catalytic hydrogenation reactions to αβ-unsaturated aldehydes

Three ruthenium complexes containing BISBI [2,2'-bis(diphenylphosphinomethyl)-biphenyl], RuCl2(PPh3)(BISBI) 1, RuH-Cl(CO)(PPh3)(BISBI) 2 and RuH2(CO)(PPh3)(BISBI) 3, had been prepared. Their compositions and structures were characterized by P-31{H-1)-NMR,H-1-NMR and elemental analysis. Results of P-31{H-1}-NMR showed that the PPh3 in complex 1 was completely dissociated and a dimer complex [RuCl2(BISBI)](2) was generated in CDCl3 and C6D6 solutions. Molecular structure of 3 was also confirmed by single-crystal X-ray diffraction, the crystal belonged to a monoclinic system, P2(1)/n space group, a=16.771(3) Angstrom, b = 20.688(4) Angstrom, c = 17.139(3) Angstrom, beta = 106.03(3)degrees, V= 5715(3) Angstrom(3) and Z = 4. The hydrogenation results revealed that the three complexes showed much higher activities and selectivities than their analogous triphenylphosphine complexes for the hydrogenation of C=O bond in citral (3,7-dimethyl-2,6-octadienal) and cinnamaldehyde. (C) 1998 Elsevier Science S.A. All rights reserved.