ther straight or branched chains that contain from 1 up to about 10 carbon atoms, and the aryl portions contain from about 4 to about 14 carbons, except the R.sup.2 is not halide, pseudohalide or higher alkyl; or,(ii) R.sup.1 and R.sup.2 together form --(CH.sub.2).sub.n, where n is 3 to 6; or,(iii) R.sup.1 and R.sup.2 together form 1,3-butadienyl; and X, R.sup.8, R.sup.9 and R.sup.10 are selected