Cationic molybdenum(IV)- and tungsten(IV)-iridium(III) complexes with hydride and eta5:eta1-cyclopentadienyl bridging ligands. Syntheses and x-ray crystal structure of [(eta5-C5H5)M(mu-H)2(mu-(eta5:eta1-C5H4))IrH(PMePh2)2][BPh4] (M = Mo and W)

Cations of the type [IrHz(solvent)2L2]+ (1; L = tertiary phosphine) react readily with the hydrido complexes [MHZ(q5-C5H5),] (M = W (3) and M = Mo (4)) to afford the dihydrido q5:q1-cyclopentadienyl-bridged complexes [(115-C5H5)M(~-H),(~-(q5:q1-C5H4))IrHLz]+ (6, M = W, and 7, M = Mo). The structures of complex cations 6 and 7 in solutions were unambiguously established by ‘H, 13C, and 31P NMR spectroscopy. The X-ray crystal structures of the [BPh4]- salts of cations 6c and 7c (L = PMePhz) were determined. The two compounds are isomorphous and belong to space group Cc; unit-cell dimensions: a = 10.736 (1) A, b = 18.872 (2) A, c = 26.060 (2) A, p = 101.43 (1)O, V = 5175 (1) A3, and 2 = 4 for [6c][BPh4] and a = 10.724 (2) A, b = 18.834 (2) A, c = 26.091 (3) A, 0 = 101.44 (3)O, V = 5165 (2) .A3, and 2 = 4 for [7c][BPh4]. The structures were refined to R = 0.045 and 0.052, respectively. The hydride ligands in [6c][BPh4] were located and refined by least squares. The geometries of the two cations are similar; the interesting difference being the metal-metal distance (W-Ir = 2.706 (1) and Mo-Ir = 2.641 (1) A). The reaction of 3 with [IrH2(acetone)2(PCy3)z]+ (le), however, follows a different well-defined stoichiometry giving 6e, [WH3- (05-CE”)~1+ (11), and [I~Hs(PCY~)ZI We).