Neutral and anionic silylmethyl complexes of the Group 3a and lanthanoid metals; the X-ray crystal and molecular structure of [Li(thf)4][Yb{CH(SiMe3)2}3Cl](thf = tetrahydrofuran)

The neutral [M(CH2SiMe3)3(thf)2](M = Tb, Er, or Yb; thf = tetrahydrofuran) and the ionic [Li(L)4]-[MR4][R = Me3SiCH2; when M = Y, Er, or Yb, L2= Me2NCH2CH2NMe2(tmed); when M = Y, L = thf], [Li(thf)4][M(Cl)R3][M = Er or Yb, R =(Me3Si)2CH], and [LiL2][M(η-C5H4SiMe3)2Cl2][L = 0·5 tmed or thf) are reported; their structures are deduced from i.r. and 13C and 1H n.m.r. (M = Y) spectra, conductivity, and in the case of [Li(thf)4][Yb{CH(SiMe3)2}3Cl], by a single crystal X-ray analysis [l(Yb–C)(av.)= 2·38 A].