No abstract

Hydrogen bonding is a topic which has received much attention over the years and continues to do so as the importance of such interactions is established in all areas of chemistry. The class of hydrogen bonds that directly involves electron-rich transition metal centres in the three-centre interaction has received little attention until quite recently. Such interactions are of importance in understanding intermolecular interactions between organometallic molecules and are particularly relevant to understanding proton transfer reactions that directly involve transition metal centres.

Reaction of silafluorene (H2SiC12H8) with (Ph3P)2Pt(η2-C2H4) in C6D6 (or C7D8) provided the trinuclear complex [(Ph3P)Pt(μ-SiC12H8)]3 (3). The structure of 3, which exhibits a nonplanar Pt3Si3 core, was confirmed by X-ray crystallography.

A dinuclear Pt−Si complex containing bridging η2-H−SiH(IMP) (IMP = 2-isopropyl-6-methylphenyl) ligands, {(Ph3P)Pt[μ-η2-H−SiH(IMP)]}2 (1) has been synthesized and characterized by NMR and X-ray crystallography. A 3c-2e nonclassical interaction between Pt···H···Si is supported by spectroscopic and crystallographic data. Complex 1 reacts with the more basic and less hindered phosphine PMe2Ph to afford a different dinuclear Pt−Si complex with loss of H2, {(PhMe2P)2Pt[μ-SiH(IMP)]}2 (2). Complex 2 was characterized by multinuclear NMR spectroscopy.

Tris(triisopropylsilyl)silane (iPr 3 Si) 3 SiH has been synthesized and studied by X-ray and neutron diffraction. It possesses an unusual structure in which the four silicon atoms are nearly coplanar, ∠Si-Si-Si ) 118.41(5)°. The Si-H distance is found to have a normal value of 1.506(2) Å. Thermal and room-temperature photochemical decomposition of (iPr 3 -Si) 3 SiH leads to the elimination of iPr 3 SiH and the generation of bis(triisopropylsilyl)silylene, [(iPr 3 Si) 2 Si:]. Reactions of (iPr 3 Si) 2 Si: include precedented insertions into H-Si bonds and addition to the π-bonds of olefins, alkynes, and dienes. Despite theoretical predictions of a triplet ground state for [(iPr 3 Si) 2 Si:], stereospecific addition to cis-and trans-2-butene was observed.