Reactions of dihydrazinium phthalate with bivalent first row transition metal nitrates

Hydrazine metal phthalate dihydrate complexes of the type M(C6H4(COO)(2))N2H4.2(H)O, where M = Mn, Co or Zn, bishydrazine metal phthalates M(C6H4(COO)(2))2N(2)H(4), where M = Mn, Fe, Co, Ni or Zn and N2H5Cu(C6H4(COOH)COO)(3).H2O have been prepared in aqueous solution from a mixture of metal nitrate hydrate, dihydrazinium phthalate and in the presence/absence of hydrazine hydrate. The compounds have been characterised by analytical, magnetic, electronic and IR spectral and thermal studies, The magnetic moment values and electronic spectral data shown suggest that the Mn, Fe, Co and Ni complexes are of the spin-free (high spin) type with octahedral geometry. The IR absorption bands of N-N stretching in the range 970-980 cm(-1) unambiguously prove the bidentate bridging nature of the N2H4 ligands. The difference between asymmetric and symmetric stretching frequencies of carboxylate groups in the range 180-260 cm(-1) confirms the unidentate coordination behaviour of OCO- groups of the phthalate dianion. The simultaneous TG-DTA curves reveal that the compounds decompose thermally by endothermic and exothermic modes. The cobalt phthalate hydrazine dihydrate complex gave a mixture of metal and metal oxide as the final product, whereas the complexes M(C6H4(COO)(2))2N(2)H(4) (M = Co, Ni or Zn) gave metal as the final product of decomposition. The complexes decompose via metal phthalate, oxalate or carbonate intermediates. The X-ray powder diffraction patterns indicate that the M[C6H4(COO)(2))N2H4.2H(2)O complexes are isostructural as are the M(C6H4(COO)(2))2N(2)H(4) complexes.