Synthesis, structure and hydrogenation catalytic activity of 3,η2-ampy)(μ,η1:η2-PhC=CHPh)(CO)6(PPh3)2> (Hampy = 2-amino-6-methylpyridine)

Article abstract of DOI:10.1016/0022-328X(94)87120-5

The compound 3,η²-ampy)(μ,η¹:η²-PhC=CHPh)(CO)6(PPh3)2> (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of 3,η²-ampy)(μ,η¹:η²-PhC=CHPh)(CO)7(PPh3)> with triphenylphosphine at room temperature.However, the reaction of 3,η²-ampy)(CO)7(PPh3)2> with diphenylacetylene requires a higher temperature (110 deg C) and does not give complex 1 but the phenyl derivative 3,η²-ampy)(μ,η¹:η²-PhC=CHPh)(μ-PPh2)(Ph)(CO)5(PPh3)> (2).The thermolysis of complex 1 (110 deg C) also gives complex 2 quantitatively.Both 1 and 2 have been characterized by X-ray diffraction methods.Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans-stilbene under mild conditions (80 deg C, 1 atm. of H2), although progressive deactivation of the catalytic species is observed.The dihydride 3,η²-ampy)(μ,η¹:η²-PhC=CHPh)(CO)5(PPh3)2> (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction. Key words: Ruthenium; X-ray diffraction; Hydrogenation; Homogenous catalysis; Clusters; Phosphine