. . "g 1-4 but preferably 1-2 carbon atoms, X is a leaving group attached to the silicon atom, for instance, Cl, OCH3, OC2H5, (CH3)2N, (CH3CH2)2N, I, Br, CN, OOCH3, O(CO)CH3, O3SCF3, where a and b are positive integers equal to 0 or 1, and a plus b equals to 1 or 2 but never 0, n is a positive integer equal to 2-8 but preferably 2." . . .