Syntheses and structures of alkyl and aryl halide complexes of the type [(PiPr(3))(2)PtH(eta(1)-XR)]BArf and analogues with Et(2)O, THF, and H-2 ligands. Halide-to-metal pi bonding in halocarbon complexes

The reaction of Pt(PiPr(3))(3) with SO2 led to the formation of (PiPr(3))(2)Pt(SO2) (1), isolated in 93% yield. The addition of [H(OEt(2))(2)](BArf)-B-+(BArf = B(3,5-(CF3)(2)C6H3)(4)) to 1 in ether at -78 degrees C afforded the solvent complex trans-[(PiPr(3))(2)Pt(H)(OEt(2))]BArf (2) in 85% isolated yield. Complex 2 served as a precursor to monodentate halocarbon complexes of the type Pt(eta(1)-XR). The dichloromethane complex trans-[(PiPr(3))(2)Pt(H)(eta(1)-ClCH2Cl)]BArf (3) was isolated in 80% yield by the recrystallization of 2 from CH2Cl2/hexane. IR spectroscopy suggested the existence of dichloromethane binding which was confirmed by X-ray crystallography. The reaction of 2 or 3 with iodo- or bromobenzene led to the isolation of the haloarene complexes trans-[(PiPr(3))(2)Pt(H)(eta(1)-XPh)]BArf, where X = I (4, 87% yield) or Br (5, 60% yield). Both compounds were characterized spectroscopically and by X-ray crystallography. An unexpected steric interaction in 4, suggested by molecular mechanics calculations to be significant, was rationalized in terms of halide-to-metal pi bonding. The PhI complex 4 decomposed under harsh conditions to the bridging iodide compound {trans-[(PiPr(3))(2)Pt(H)](2)(mu-I)}BArf (6) which was structurally characterized. The THF adduct [(PiPr(3))(2)Pt(H)(THF)]BArf (7), isolated in 78% yield and also characterized by X-ray crystallography, was formed when any of the compounds 2, 3, 4, or 5 was dissolved in THF. The CH2Cl2 complex 3 reacted with H-2 to form the dihydrogen complex tans-[(PiPr(3))(2)Pt(H)(eta(2)-H-2)]BArf which was characterized by NMR spectroscopy.