Abstract: A nitrogen complex of an inorganic phosphate comprising the anionic sub-structure (I); whereby a nitrogen atom (N) of a complexing agent is complexed to an oxygen atom (O) of the inorganic phosphate; wherein the nitrogen atom is selected from the group consisting of a nitrogen atom of an amine group or a nitrogen atom of a N-heteroaromatic ring; and wherein A and A? are each independently selected from the group of constituents consisting of a hydroxyl group (—OH), an oxide group (—O?), the group —OR where R is alkyl or substituted alkyl; an oxygen to which a nitrogen is complexed (—0?N) wherein the nitrogen atom is selected from the group consisting of a nitrogen atom of an amine group or a nitrogen atom of a N-heteroaromatic ring; and a phosphate of the form (i); wherein each of A? and A?? are selected independently from the same group of substituents as A and A?; wherein at least one of A, A?, A? and A?? is an oxide (—O?) with the proviso that when A? and A?? are not present then at least one of A and A? i