Abstract: The invention concerns novel compounds of the formula I ##STR1## wherein: Z is selected from oxygen and the group --YAn wherein Y is selected from C.sub.1 to C.sub.6 alkyl and benzyl and An is an anion;k is zero or the integer 1;n is an integer selected from 3 and 4;X is selected from halogen, nitro, cyano, alkyl, substituted alkyl, hydroxy, alkoxy, substituted alkoxy, alkenyl, alkenyloxy, alkynyl, alkynyloxy, acyloxy, alkoxycarbonyl, alkylthio, alkylsulfinyl, alkylsulfonyl, sulfamoyl, substituted sulfamoyl, alkanoyloxy, benzyloxy, substituted benzyloxy, amino, substituted amino and the groups formyl and alkanoyl and the oxime, imine and Schiff base derivatives thereof;R.sup.1 is selected from hydrogen, alkyl, alkenyl, alkynyl, substituted alkyl, alkylsulfonyl, arylsulfonyl, acyl and an inorganic or organic cation;R.sup.2 is selected from alkyl, substituted alkyl, alkenyl, haloalkenyl, alkynyl and haloalkynyl;R.sup.3 is selected from alkyl, fluoroalkyl, alkenyl, alkynyl, and phenyl; andR.sup.