Preparation, characterization and solid state thermal studies of cadmium(II) squarate complexes of ethane-1,2-diamine and its derivatives

[CdL3]C4O4 [L=ethane-1,2-diamine (en)], [CdL2(H2O)(2)]C4O4 [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten), N-propylethane-1,2-diamine (pren), propane-1,2-diamine (pn) and N-methylpropane-1,2-diamine (ibn)] and [CdL2(C4O4)] [L=N-isopropylethane-1,2-diamine (ipren)] have been synthesized by the addition of the respective diamine to finely powdered CdC4O4. 2H(2)O and their thermal studies have been carried out in the solid state. [Cd(en)(3)]C4O4 upon heating loses two molecules of diamine in two overlapping steps yielding Cd(en)C4O4 which upon further heating transforms to unidentified products. The diaquabis(diamine) species, [CdL2(H2O)(2)]C4O4, show thermally induced deaquation-anation reaction in the solid state and thereby produce [CdL2(C4O4)], which reverts on exposure to humid atmosphere (RH=90%) for 20-24 h. All the squarato bis(diamine) species, [CdL2(C4O4)], on pyrolysis in the solid state transform to unidentified products through the formation of intermediates, CdL1.5C4O4, (L=meen, pren and ipren), CdLC4O4 (L=meen, eten, pren, ipren, pn and ibn) and CdL0.5C4O4 (L=eten, pn and ibn). However, amongst the intermediates only the mono diamine species, CdLC4O4 can be isolated in pure form and the pyrolytic process is the only way to synthesize them. The monodiamine species can be stored in a desiccator as well as in an open atmosphere and proposed to have a polymeric structure.