Novel chain polymers by condensation of metal(II) coordinated salicylaldehyde with diamines

Coordination polymers, {article}{empty}{document}-- (MtL-- )ₙ{document} were synthesized by condensation of bis(salicylaldehydo)‐metal(II) (metal = Co, Ni, and Cu) with diamines (1, 4‐diaminobenzene and 4,4′‐diaminobiphenyl). Their composition, structure, thermal stability, and physical properties were investigated by analytical, magnetic, spectral (IR and DRS), the thermogravimetric studies. It was found that in the bis(salicylaldehydo)metal(II)‐chelates, two salicylaldehyde molecules are linked to each metal ion through the oxygen atoms of the phenolic and aldehydic groups and in the polymeric complexes the nitrogen atoms of the amino groups replace the aldehyde oxygens. The diamine molecule is thus acting as a bridging unit between two salicylaldehydometal(II) units, forming structures 1 and 2. The polymers obtained from 4,4′‐diaminobiphenyl (2a−c) are thermally more stable than those from 1, 4‐diaminobenzene (1a−c), the order of thermal stability in both cases being Ni(II) > Cu(II) > Co(II). Co(II) and Cu(II)‐complexes are paramagnetic, whereas Ni(II)‐complexes are diamagnetic. The reflectance spectra along with the magnetic data suggest a square planar structure for Cu(II) and Ni(II)‐complexes, and a tetrahedral one for the Co(II)‐complexes.