Binuclear Hydridoplatinum(II): One-Pot Synthesis, INS Spectra and X-ray Crystal Structure of [Pt2(dcype)2(H)3][BPh4] {dcype = 1,2-Bis(dicyclohexylphosphanyl)ethane}

The binuclear platinum(II) hydride [Pt2(dcype)2(H)3][Cl] (1b) has been isolated in high yields by treatment of Pt(dcype)Cl2 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 [Pt2(dppp)2(H)3][OH] (3b) and [Pt2(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 {[Pt2(dppe)2(H)3]+, 5} and trinuclear {[Pt3(dppe)3(H)3]+, 6} trihydrides were obtained with the dppe ligand. Various salts of the cation 1, [Pt2(dcype)2(H)3][X] (X = BF4, 1a; OH, 1c; BPh4, 1d), were isolated either from [Pt(dcype)(?-OH)]2[BF4]2 (2) by a general procedure (1a), or by decomposition of the complex cis-[Pt(dcype)(H)2] in solution (1c), as well as by metathesis reactions (1a, 1c, and 1d). Compounds 1a, 1b, and 1d react with CO under mild conditions to afford the corresponding PtI binuclear hydrides [Pt2(dcype)2(?-CO)(?-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 (1H, 31P, and 195Pt) spectroscopic techniques; the 1 and 7 cations show fluxional behaviour on the NMR timescale. The structure of compound 1d was determined, at 200 K, by single-crystal X-ray diffraction. All the hydrido ligands were located. The Pt-Pt separation is 2.696(1) A and the coordination geometry around each platinum centre can be regarded as distorted square planar. Incoherent Inelastic Neutron Scattering (INS) spectra were obtained for 1a and [Pt2(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