SYNTHESIS AND STRUCTURE OF OLIGOMERIC DIMESITYLGERMYL-SUBSTITUTED CARBODIIMIDES - CHARACTERIZATION OF HIGHER OLIGOMERS

New cyclic oligomers of dimesitylgermylene carbodiimides (Mes(2)GeNCN) (n) (n = 3 (1) and 4 (2)) were synthesized by reactions of dimesityldi chlorogermane with either cyanamide in the presence of triethylamine o r lithium cyanamide. The reactions always gave 1, the trimer of the hy pothetical (Mes(2)Ge = N - CN), as the major compound. Higher oligomer s 3 (n up to 20 - 30) also can be isolated, depending on the reaction conditions. In THF solution at room temperature, 2 and 3 slowly isomer ize to 1, which seems to be the most stable compound. X-ray analysis o f trimer 1 and tetramer 2 shows unstrained tetrahedral germanium atoms and linear diimine linkers.