Silyl, hydrido-silylene, or other bonding modes:: Some unusual structures of [(dhpe)Pt(SIHR2)]+ (dhpe = H2P-CH2-CH2-PH2; R = H, Me, SiH3, Cl, OMe, NMe2) and [(dhpe)Pt(SiR3)]+ (R = Me, Cl) from DFT calculations

DFT (B3LYP) calculations have been carried out in order to quantitatively evaluate the energies and stereochemistry of the accessible structures of [(dhpe)Pt(SiHR2)](+) (dhpe = H2P-CH2-CH2-PH2; R = H, CH3, SiH3, Cl, OMe, SMe, NMe2) and of [(dhpe)Pt(SiR3)](+) (R = CH3, Cl). A number of different isomers have been located. The expected terminal silyl or hydrido-silylene complexes are often not the most stable complexes. An isomer in which an H or an R group bridges a Pt=SiHR or Pt=SiR2 bond is found to compete with the terminal silyl or hydrido-silylene isomers. In some cases, isomers derived from cleavage of a C-H bond and formation of a silene or disilene ligand are obtained. The structures of the platinum silyls differ from that of the equivalent alkyl complex, calculated for [(dhpe)Pt(CH3)](+).