Subvalent group 14 metal compounds XI. Oxidative addition reactions of organic halides or acid anhydrides (including CH44-nCln, PhBr, BrN(SiMe3)2, ButCOCl, or (CF3CO)2O) to some bivalent group 14 metal amides or alkyls

Article abstract of DOI:10.1016/0022-328X(87)80276-0

Oxidative reactions are reported of alkyl or phenyl halides, the chloromethanes CH_4-nCl_n (n = 2, 3, or 4), or N-bromohexamethyldisilazane with (i) some bulky germanium(II), tin(II), or lead(II) amides, or (ii) bistin(II).Similar reactions with pivaloyl or benzoyl chloride, or trifluoroacetic anhydride, produced stable, yellow α-keto-germanes and stannanes.The following new compounds have been isolated and characterised: Sn(NR2)(R')X, (R = SiMe3; R'X = BuⁿCl, MeBr, EtBr, PrⁿBr, Bu^tBr, PhBr, MeI, EtI, PrⁱI, BuⁿI, PhI, CCl4, CHCl3, or CH2Cl2), MBr(NR2)3 (M = Ge, Sn, or Pb; R = SiMe3), SnBr(NR2) (TMPPD)2 CMe2(CH2)3C<*>Me2>.SnIMe(TMPPD)2, Sn(CHR2)3I, M'(COR )Cl(TMPPD)2 (M' = Ge or Sn, R = Ph or Bu^t), Sn(CHR2)2(COR )Cl, M'(COCF3)(NR2)2(OCOCF3), M'(COCF3)(TMPPD)2, and M'(COCF3)(NBu^t2)2(OCOCF3).The α-keto-germanes and stannanes are particularly noteworthy.The acyl chloride 1/1 adducts (which are sparingly soluble in hydrocarbons) show two carbonyl stretching modes in the region 1635 - 1690 cm^-1 which is attributed to the presence of two isomers as a conseqence of restricted rotation about the M' <*> C(=O)R bond.This effect is not observed in the bis(amido)metal 1/1 adducts with (CF3CO)2O probably because the ^-OC(O)CF3 ligand, being sterically much more demanding than Cl^-, directs the formation of a single rotamer.The mass spectral fragmentation pattern of GeBr3 is reported.The halogenohydrocarbon addition reactions to the amides M'(NR2)2 (R = SiMe3) are believed to involve a free radical pathway, with ^.M'(NR2)2X as an intermediate.The reaction of Sn(NR2)2 with excess of PhBr is pseudo first-order, and is catalysed by a trace of EtBr.The uncatalysed reaction yields exclusively SnBr(NR2)2Ph in C6H6, whereas in THF SnBr2(NR2) is a significant by-product.Crystalline SnBr3 is a monomer, with Sn-Br 2.579(2) Angstroem, Sn-N 2.056(7) Angstroem, Br-Sn-N 102.4(2) grad, and N-Sn-N' 115.5(1) grad; the nitrogen environment is trigonal planar.