Abstract: Compounds of the general formula I ##STR1## where the symbols n independently of one another are each 0, 1 or 2, m is 0 or 1, A.sup..crclbar. is an anion, the radicals X independently of one another are each hydrogen, methyl or ethyl and the radicals R independently of one another are each hydrogen, unsubstituted or substituted alkyl, cycloalkyl or aryl, or two adjacent radicals R may furthermore be alkylene or, together with the carbon atoms to which they are bonded, may form an unsaturated or aromatic ring, with the proviso that one or more symbols n are not 0.