Phosphine (PH 3) complexes of ruthenium, osmium and iridium as precursors of terminal phosphido (PH 2) complexes and the crystal structure of [Os(μ2-PH 2) Cl(CO) (PPh 3) 2]2 · (C2H 2Cl 4) 4

Abstract

Stable phosphine complexes MHCl(PH 3)(CO)(PPh 3) 2 (M = Os, 1a, M = Ru, 1b and IrHXCl(PH 3)(PPh 3) 2 (X = H, 2, X = Cl, 3) have been prepared by substitution of phosphine for a labile triphenylphosphine in tris(triphenylphosphine) precursors. Strong acids (e.g. aqueous HClO 4 in CH 3CN) cleave the hydridemetal bonds in 1a, 1b to give [MCl(PH 3)(NCCH 3)(CO)(PPh 3) 2]ClO 4 9a, 9b as a mixture of isomeric complexes. The ligands Cl −, PMe 3, and CO can be substituted for the labile acetonitrile in 9a to give OsCl 2(PH 3)(CO)(PPh 3) 2 12 [OsCl(PH 3)(PMe 3)(CO)- (PPh 3) 2]ClO 4 10 and [OsCl(PH 3)(CO) 2(PPh 3) 2]ClO 4 11, respectively. Base deprotonates 10 and 11 to give stable isolable terminal phosphido complexes OsCl- (PH 2)L(CO)(PPh 3) 2 (L = CO, 14, L = PMe 3, 15, but when 9a is deprotonated, acetonitrile is also lost and a dimeric complex [Os(μ2-PH 2)Cl(CO)(PPh 3) 2] 2 13 is formed. The colourless crystals of 13 are triclinic with space, group P 1 , a 14.101(4), b 15.091(5), c 11.708(5) Å, α 96.68(3), β 91.71(3), γ 63.92(2)°, Z = 1, V = 2222.0 Å 3. The final refinement gave R = 0.0589, R w = 0.0603 for 4865 observed reflections. Phosphine oxidatively adds to Os(CO) 2(PPh 2) 3 to give the stable hydride-phos-phido-complex, OsH(PH 2)(CO) 2(PPh 3) 2 19.