Hydrazinium metal oxalates

Other double salts, the double oxalates of metals with monocation like alkali metal, and so on, are somewhat rare since oxalate anion precipitates metals as insoluble metal oxalates. Hence, special methods are needed to synthesize double oxalates. 

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All these complexes have been investigated by infrared, electronic, and ESR spectroscopy. Magnetic studies were carried out using a Gouy balance at room temperature. Tables 5.7 and 5.8 list, respectively, the IR absorption frequencies and the electronic spectral details and magnetic data of hydrazinium metal oxalates. 

Gajapathy, D., Govindarajan, S., Patil, K.C., and Manohar, H. (1983) Synthesis, characterisation and thermal properties of hydrazinium metal oxalate hydrates. Crystal and molecular structure of hydrazinium copper oxalate monohydrate. Polyhedron, 2, 865-873. 

Hydrazinium transition metal oxalates of Co, Ni, and Cu are prepared by mixing aqueous solutions of respective metal nitrate hydrates and hydrazinium oxalate (N2H5)2C204 (mole ratio of 1 4) and keeping the mixture at 5 °C for a couple of days. The rate of product formation increases in the order Co < Ni < Cu. The cobalt compound is somewhat unstable and it decomposes in air. Efforts to prepare the corresponding Mn, Fe, and Zn compounds using a similar procedure yielded only the simple metal oxalates [20] ... 

From the corresponding metal nitrates and hydrazinium oxalate salts ... 

Govindarajan, S. (1983) Structural and thermal studies on hydrazinium (1-I-) metal sulfate and oxalate complexes. Ph.D Thesis, Indian Institute of Science, Bangalore. 

These studies have clearly shown the presence of a hydrazinium cation coordinated to the metal ion. Interestingly, the hydrazinium cation is both coordinated and non-coordinated to metal ions in some oxalate and chloride complexes. The valence or oxidation number of metal ion appears to dictate the bonding. 

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