In the above formula I, R is an alkylene radical containing at least three carbon atoms and at least 1 nitrogen atom therein bonded to each (H NCO-Q-tO form (HzNCON g I least one (1) free valence of is bonded to an alkylene carbon atoms of R, any other free valences thereof are bonded to either hydrogen, alkyl, aryl, cycloalkyl, aralkyl, and the like; any nitrogen in R is separated from silicon by