Nickel stabilizers for synthetic polymers

Compounds of the formula I ##STR8## wherein either R.sup.1 is hydroxyl and R.sup.2 is hydrogen or R.sup.1 is hydrogen and R.sup.2 is hydroxyl, R.sup.3 and R.sup.4 are hydrogen or alkyl with 1-5 C atoms, either p is 1 and q is 1 or p is 2 and q is zero, X is optionally hydroxyl-substituted alkyl, cycloalkyl, aryl, alkaryl or aralkyl, m is a value from 1-2 and, if q = 1, can also be zero, n represents a value from 0 to 2 and L denotes a ligand R.sup.5 --N(R.sup.6)--R.sup.7, in which R.sup.5 represents alkyl, alkoxyalkyl, alkylthioalkyl, aryl, aralkyl or cycloalkyl and R.sup.6 represents H, alkyl, aralkyl or cycloalkyl and R.sup.7 is H, alkyl or aralkyl.