. . . "sub.6 alkenyl, phenyl or naphthyl orR.sup.5 and R.sup.6, together with the linking nitrogen, are thiazole, imidazole, pyrazole, triazole, pyrrolidine, piperazine, piperidine or morpholine,X is a sulfur atom or the group ##STR75## wherein R.sup.7 and R.sup.8 are each independently of the other C.sub.1 -C.sub.6 alkyl or C.sub.3 -C.sub.4 alkenyl or can also be linked to each other to form a 5- or 6-m" .