Hydrido-silyl-komplexe: VII. Strukturchemische und 29Si-NMR-spektroskopische untersuchungen an C 5R′ 5(CO)(L)Mn(H)SiR 3. Einfluss der substituenten R und R′ sowie des liganden L auf die Mn,H,Si-dreizentrenbindung

Abstract

In C 5R′ 5(CO)(L)Mn(H)SiR 3 complexes the oxidative addition reaction of the silane HSiR 3 with the C 5R′ 5(CO)(L)Mn fragment (L = CO, PR 3, P(OR) 3, CNR) is incomplete. These compounds contain Mn,H,Si two-electron three-center bonds in their ground states, which are strongly influenced by electronic and steric properties of both the metal complexes moiety and the silyl group. 29Si NMR spectroscopic investigation of complexes with different ligands L or substituents R and R′, and structure analyses reveal, that the coupling constant J(SiMnH) and the MnSi distance are especially good indicators for changes in the bonding situation. Electron-donating ligands and/or electronegative substituents R favour addition of SiR 3, as indicated by small J(SiMnH) values and short MnSi distances in the particular complexes. By means of a neutron diffraction study of MeCp(CO) 2Mn(H)SiFPh 2 ( 1) (MnSi 235.2(4), MnH 156.9(4), SiH 180.2(5) pm) and X-ray structure analyses of MeCp(CO)(PMe 3)Mn(H)SiHPh 2 ( 2) (MnSi 232.7(1) pm) and C 5Me 5(CO) 2Mn(H)SiHPh 2 ( 3) (MnSi 239.5(1) pm) structural parameters which are typical for the three-center bonds, are discussed. By comparison of known structures the reaction pathway for the oxidative addition (reductive elimination) of silanes can be derived.