Preparation, Characterization, and Thermal Reactivity of Divalent Transition Metal Hydrazine Pyridine‐2,n‐dicarboxylates (n = 3, 4, 5, and 6)

Abstract Metal hydrazine pyridine‐2,n‐dicarboxylate hydrates [M(L)N2H4 · xH2O, where L = pyridine‐2,n‐dicarboxylate dianion and x = 1–3] of cobalt, nickel, zinc, and cadmium with quinolinic (n = 3), isocinchomeronic (n = 5), and dipicolinic (n = 6), and nickel and cadmium with lutidinic (n = 4) acids have been prepared and characterized by analytical, spectroscopic, thermal, and x‐ray powder diffraction studies. Electronic spectra and magnetic susceptibility measurements indicate that all the cobalt and nickel complexes are high‐spin octahedral in nature. The IR data document the existence of bidentate bridging hydrazine [ν(N–N) = 990–965 cm−1] and tridentate pyridinedicarboxylates in all the complexes. On heating they lose their hydrated water molecules in one or two steps. The anhydrous compounds undergo exothermic dehydrazination between 200 and 330 °C followed by decomposition of the organic component to give either the corresponding metal oxide or a mixture of metal oxide and metal carbonate as the final residue. The coordination of water has been substantiated by thermal analyses.