Binuclear Hydridoplatinum(II): One-Pot Synthesis, INS Spectra and X-ray Crystal Structure of [Pt2(dcype)2(H)3][BPh 4] {dcype = 1,2-Bis(dicyclohexylphosphanyl)ethane}

Article abstract of DOI:10.1002/ejic.200300252

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; BPh ₄, 1d), were isolated either from [Pt(dcype)(μ-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 Pt^I binuclear hydrides [Pt₂(dcype)₂(μ-CO)(μ-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 la and [Pt₂(dppe)₂(H)₃][BF₄] (5a); the spectra reflect the different geometries of the two "P₄Pt ₂(H)₃" cores as found by single-crystal structure determinations. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.