Reactions of carbofunctional organosilicon compounds with N, N-dimethyI-N'-trimethylsilylhydrazine and N,N-dimethyl-N',N'-bis(trimethylsilyl)hydra~ne were studied.The composition and structure of the reaction products were found to be dependent on the reagent nature and the reaction conditions. 1,4-Dimethylamino-2,2,5,5-tetramethyl-l,4-diaza-2,5-disilaeyclohexane, a first representative of a new type of 2,5-disilapiperazines, was synthesized. A scheme of its formation was proposed.