BIS(METHYLELEMENT)DITHIOOXAMID-DERIVATE VON Al, Ga, In, Si, Ge UND Sn; PLANARE METALLABICYCLEN UND VERDRILLTE STRUKTUREN

Article abstract of DOI:10.1016/S0022-328X(00)98648-0

When trimethyl derivatives of aluminium, gallium and indium are reacted with dithiooxamides, (HNR-CS-)2 (R=H, Me, SiMe3), in a 1/2 molar ratio, 2 moles of methane are set free, and monomeric bis(dimethylmetal)dithiooxamides are formed.By 1H NMR, IR and Raman spectroscopy, two structural isomers have been established for these metalla complexes, both with a planar molecular back-bone of two fused five-membered rings, but different coordination of the two metal atoms (E- and Z-form); the centrosymmetric E-form has been characterized also by X-ray crystallography.Equivalent bis(trimethylelement)dithiooxamides of Si, Ge and Sn are obtained from the reaction of trimethylelement chlorides and N,N'-dimethyldithiooxamide.The stannyl derivative once again displays the planar bicyclic structural principle; for the silicium and germanium complexes, on the other hand, a non-chelate structure is established crystallographically where the two thiocarboxamide moieties are rotated by about 80^o.In solution, the crystal modification isomerizes into an equilibrium mixture of three rotamers; their configuration is discussed in terms of 1H NMR spectral evidence (e.g. stepwise signal coalescence).