There are disclosed novel compounds which are represented by the formula ##STR1## wherein X represents the nonmetallic atoms necessary to form a nucleus which completes a 5- or 6-membered heterocyclic moiety, R is H, an alkali metal or a group which is cleavable in aqueous alkaline medium and Z is H, alkyl having from 1 to 10 carbon atoms, aralkyl such as benzyl or phenethyl, phenyl or substituted phenyl. The compounds are useful in photographic applications.