Binuclear hydridoplatinum(II): One-pot synthesis, INS spectra and X-ray crystal structure of [Pt-2(dcype)(2)(H)(3)][BPh4] {dcype=1,2-bis(dicyclohexylphosphanyl)ethane}

The binuclear platinum(II) hydride [Pt-2(dcype)(2)(H)(3)][Cl] (1b) has been isolated in high yields by treatment of Pt(dcype)Cl-2 with NaBH4 (molar ratio 1:2) in ethanol solution at room temperature. This one-pot synthesis is not straightforward when starting from diphenylphosphanylalkane complexes. The compounds [Pt-2(dppp)(2)(H)(3)][OH] (3b) and [Pt-2(dppb)(2)-(H)(3)][OH] (4) were isolated by starting from the mononuclear hydrides (cis-[Pt(P-P)(H)(2)]} while mixtures of both binuclear {[Pt-2(dppe)(2)(H)(3)](+), 5} and trinuclear {[Pt-3(dppe)(3)(H)(3)](+), 6} trihydrides were obtained with the dppe ligand. Various salts of the cation 1, [Pt-2(dcype)(2)(H)(3)1][X] (X = BF4, 1a; OH, 1c; BPh4, 1d), were isolated either from [Pt(dcype)(mu-OH)](2)[BF4](2) (2) by a general procedure (1a), or by decomposition of the complex cis-[Pt(dcype)(H)21 in solution (1c), as well as by metathesis reactions (1a, 1c, and 1d). Compounds la, 1b, and 1d react with CO under mild conditions to afford the corresponding Pt-I binuclear hydrides [Pt-2(dcype)(2)(mu-CO){mu-H)][X] (X = Cl, 7a; BF4, 7b; BPh4, 7c). The binuclear core of cation 1 is broken by KCN in methanol solution, yielding the mononuclear complex cis-[Pt(dcype)(CN)(H)] (8). The complexes 1a-d, 2, 7a-c, and 8 have been characterised by FAB MS, IR, and NMR (H-1, P-31, and Pt-195) spectroscopic techniques; the 1 and 7 cations show fluxional behaviour on the NMR timescale. The structure of compound Id was determined, at 200 K, by single-crystal X-ray diffraction. All the hydrido ligands were located. The Pt-Pt separation is 2.696(l) Angstrom and the coordination geometry around each platinum centre can be regarded as distorted square planar. Incoherent Inelastic Neutron Scattering (INS) spectra were obtained for la and [Pt-2(dppe)(2)(H)(3)][BF4] (5a); the spectra reflect the different geometries of the two "P4Pt2(H)(3)" cores as found by single-crystal structure determinations. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).