This third review in a series involving reactions of hydrosilanes and transition metal complexes and characterization of the products covers the period 2009 thru 2013. After a brief discussion of other synthetic methods used for the formation of Si-TM complexes, Section 3 provides an extended discussion of the types of ligands and metal complexes used as reactants with hydrosilanes. The increase in use of pincer ligands in forming stable, isolable complexes is featured. Three tables list the complexes reported for primary, secondary, and tertiary silanes. Many reactions leading to SiTM complexes are initiated by loss of a ligand prior to oxidative addition of the hydrosilane or by a metathesis reaction. Structural data are tabulated for the isolated complexes and provide the Si-TM bond ranges for the elements in the “d” block. A major section on nonclassical (σ or agostic) complexes includes two general groupings with Si–H···TM and M–H···Si interactions. A section on solution processes identified by NMR spectroscopy is dominated by hydride exchange examples. A section on bonding outlines a unifying bonding description that has been proposed as well as calculations reported for Si-TM complexes, both real and hypothetical examples.

Addition of the THF-insoluble di-Grignard reagent from 2,2′-dibromo-4,4′-tert-butylbiphenyl (1) to a solution of [(teeda)·H2SiCl2] in CH2Cl2/THF produced 2,7-di-tert-butyl-9H-9-silafluorene (3) in isolated, recrystallized yields of <20%. The related soluble dilithio reagent from bis(2-bromo-4-methylphenyl)methylamine (2) formed in Et2O, when reacted with [(teeda)·H2SiCl2] in CH2Cl2/Et2O, gave similar yields of 5,10-dihydro-2,5,8-trimethylphenazasiline (4). In the absence of CH2Cl2 the major product produced from 1 was the spirocycle 2,2′,7,7′-tetra-tert-butyl-9,9′-spirobi[9H-9-silafluorene] both in a solvent-free form (5′) and as an ethanol solvate (5), both of which were crystallographically characterized. The spirocycle 2,2′,5,5′,8,8′-hexamethyl-5,10-dihydro-10,10-spirobiphenazasiline (6) was formed from the reaction of the dilithio reagent of 2 in the absence of CH2Cl2.

Kinetic data were obtained for the halide induced epimerization of meso-X[(p-RC6H4)MeSi]2X (halide=Cl− where X=F, R=H, CH3O, CH3, F, CF3; halide=Br− where X=Cl, R=H) to a 1:1 meso:racemic mixture of diastereomers. A Hammett plot demonstrates a correlation of the rate of epimerization of the fluorinated derivatives with electropositive character at silicon. In order to extend the series of para-substituted derivatives, F[(p-RC6H4)MeSi]2F (R=CF3) was prepared by treatment of H[(p-RC6H4)MeSi]2H (R=CF3) with CuCl2/CuI/KF in THF and the meso diastereomer was resolved via crystallization induced asymmetric transformation and the structure verified by X-ray crystallography. Possible mechanisms for the halide induced epimerization are discussed.The 1,2-difluorodisilane, meso-F[(p-CF3C6H4)MeSi]2F, was prepared and crystallographically characterized. Kinetic data were obtained for the halide induced epimerization of meso-X[(p-RC6H4)MeSi]2X (halide=Cl− where X=F, R=H, CH3O, CH3, F, CF3; halide=Br− where X=Cl, R=H) to a 1:1 meso:racemic mixture of diastereomers and possible mechanisms are discussed.