The synthesis and crystal structure of (η 5-C 5H 5)NiOs 3(μ-H) 3(CO) 8(Ph 2PCCPr i) and of (η 5-C 5H 5)NiOs 3(μ-H) 3(CO) 8{(Ph 2PCCPr i)Co 2(CO) 6}(σ-P,η 2-C 2). The reaction of unsaturated “linear” ligands on clusters with metal carbonyl species

Abstract

The complex (η 5-C 5H 5)NiOs 3(μ-H) 3(CO) 8(Ph 2PCCPr i ( 2a) has been obtained by treating (η 5-C 5H 5)NiOs 3(μ-H) 3(CO) 9 ( 1) with PPh 2C 2Pr i in the presence of Me 3NO. Treatment of 2a with Co 2(CO) 8 in hexane at room temperature gives high yields of (η 5-C 5H 5)NiOs 3(μ-H) 3(CO) 8{(Ph 2PCCPr i)Co 2(CO) 6} ( 3). The complexes 2a and 3 have been characterized by means of elemental analyses and IR, 1H and 13C NMR spectroscopies. Their structures have been determined by X-ray methods. Crystals of 2a are triclinic, space group P 1 with Z = 4 in a unit cell of dimensions a 16.543(7), b 16.578(7), c 16.461(6) Å, α 116.6(3), β 94.1(2), γ 118.8(3)°. Crystals of 3 are monoclinic, space group P2 1/ n with Z = 4 in a unit cell of dimensions a 18.275(9), b 17.804(7), c 13.343(4) Å, β 106.46(3)°. Both structures were solved by direct and Fourier methods and refined by full-matrix least-squares to R = 0.055 for 5882 observed reflections for 2a and to R = 0.046 for 1848 observed reflections for 3. Both structures can be derived from that of 1 (having a tetrahedral NiOs 3 core with three hydridic hydrogen atoms bridging the OsOs edges, a cyclopentadienyl group coordinated to the Ni atom, and nine terminal carbonyls bound to the Os atoms, three for each Os atom) by replacing one of the axial carbonyls by the Ph 2PCCPr i ligand. In 3 a Co 2(CO) 6 unit interacts, through two π bonds, with the acetylenic CC bond of the phosphino-alkyne ligand.