Synthesis, Crystal Structure, and Properties of a Binuclear Co(II)‐tpha Complex (tpha = Terephthalate Dianion)

Abstract

The binuclear complex [Co2(tpha)(phen)4(H2O)2]·(NO3)2·2C2H5OH, (tpha = terephthalate dianion; phen = 1,10‐phenanthroline) has been synthesized by the reaction of H2tpha, phen and Co(NO3)2·6H2O in a mixed solvent of DMF/C2H5OH. Its structure was solved at 296 K. The compound crystallizes in the monoclinic system, space group P21/c: a = 0.9687(1) nm, b = 1.2988(3) nm, c = 2.2627(3) nm, β = 97.49(1)°, Z = 2. The final agreement factors are R = 0.052 and wR = 0.062. The binuclear entity is centrosymmetric and each Co(II) ion is 6‐coordinate, distorted octahedral. The tpha ligand bridges two Co(II) ions in a bis‐monodentate fashion. The cations and anions are linked through intramolecular hydrogen bonds. The result of the variable temperature magnetic susceptibility measurement revealed antiferromagnetic interaction between the two Co(II) ions. The analysis of the magnetic data finds: 2J = −0.45 cm−1 and g = 1.94. Also, the ESR spectra and the color of the complex markedly vary with temperature. The IR and UV‐Vis‐NIR spectra of the complex have been determined and assigned.