Reactions of Na[Mo(CO) 3( η5-C 5H 5)] towards CoCl(PPh 3) 3 and CoCl(P(OMe) 3) 5: X-ray crystal structures of [MoCo(CO) 6(PPh 3)( η5-C 5H 5)] and [Mo(CO) 3(P(OMe) 3)( η5-C 5H 5)] 2

Abstract

Reaction of Na[Mo(CO) 3( η 5-C 5H 5)] with CoCl(PPh 3) 3 in tetrahydrofuran under 1 atm of CO yielded two heterobimetallic compounds: [MoCo(CO) 5(PPh 3) 2( η 5-C 5H 5)] ( 1a) and [MoCo(CO) 6(PPh 3)( η 5-C 5H 5)] ( 1b). Both compounds were characterized by mass, IR, 1H, 13C and 31P NMR spectra. The X-ray crystal structure of 1b was determined. The cobalt centre of 1b has acquired three carbonyl groups and released two triphenylphosphine ligands during the reaction. The only PPh 3 which remained on the cobalt centre was in the axial position of the trigonal bipyramidal structure, thus avoiding steric interaction with ligands from the molybdenum fragment. The molybdenum centre is in a ‘four-legged piano stool’ configuration. From the reaction of Na[Mo(CO) 3( η 5-C 5H 5)] and CoCl(P(OMe) 3) 5 in tetrahydrofuran, an unexpected bimetallic compoun[ [Mo(CO) 2(P(OMe) 3( η 5-C 5H 5)] 2 ( 6) was obtained which was characterized by mass, IR, 1H, 13C and 31P NMR spectra. The molecular structure of 6 was also determined by X-ray diffraction. The centrosymmetric complex is a typical four-legged piano-stool dimer. The MM bond length (3.239 Å) is longer than the sum of the metal radii.