Compounds of the formulae ##STR00001## ##STR00002## wherein Z is OR.sub.1, SR.sub.1, or NR.sub.1R.sub.2, Y is OR.sub.3, SR.sub.3, or NR.sub.3R.sub.4, at least one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 is hydrogen, at least one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 is other than hydrogen, at least one Z or Y within the compound is NR.sub.1R.sub.2 or --NR.sub.3R.sub.4, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, and R.sub.7 each, independently of the others, is hydrogen, alkyl, aryl, arylalkyl, or alkylaryl, and wherein R.sub.7 can also be (vi) an alkoxy, aryloxy, arylalkyloxy, alkylaryloxy, polyalkyleneoxy, polyaryleneoxy, polyarylalkyleneoxy, polyalkylaryleneoxy, silyl, siloxane, polysilylene, polysiloxane, or ##STR00003## wherein X is a direct bond, oxygen, sulfur, NR.sub.40-- wherein R.sub.40 is hydrogen, alkyl, aryl, arylalkyl, or alkylaryl, or CR.sub.50R.sub.60-- wherein R.sub.50 and R.sub.60 each, independently of the other, is hydrogen, alkyl, aryl, arylalkyl, or alkylaryl, and wherein R.sub.6 can also be ##STR00004##