Zinc complexes of condensed phosphates, 3 - Diphosphate-zinc complexes with tridentate coligands

Diorganodiphosphates (POP2-) and a triorgano-methylenedi-phosphonate (PCP-) have been combined with zinc salts and the tridentate Ligands L [L = bis(b enzimidazolylmethyl)amine, bis(2-pyridylmethyl) amine, triazacyclononane, t rimethyltriazacyclononane, and (dimethylaminoethyl) (2-pyridylmethyl)amine] . The resulting ternary complexes have been found to contain four-, five-, or six-coordinate zinc. Four-coordinate zinc has been identified in the com plex types [L . Zn(PCP)](+) and [L . Zn(POP)Zn .L]2(+,) containing monodent ate phosphate Ligands. Five-coordinate zinc has been found in the complexes [L . Zn(POP)] with chelating diphosphate ligands. Six-coordinate zinc has been observed in the complex type [L.Zn(POP).H2O] containing chelating diph osphates and in the complex type [L . Zn(POP)](2) in which the diphosphates act as tridentate bridging ligands. In a few cases, hydrolytic cleavage of the diphosphates resulted in the isolation of the trinuclear complexes [(L . Zn)(3)(ROPO3)(2)] HPO4 containing triply-bridging monophosphates.