Syntheses, characterization, thermal properties and single crystal structure determination of cobalt(III) complexes with 2,2 '-biimidazole and 1,10-phenanthroline ligands


A novel mixed ligand cobalt(III) complex, [Co(phen)(2)(Hbiim)]Cl-2 center dot 10H(2)O, has been utilized in the syntheses of three halogenocadmate(II) complexes [Co(phen)(2)(Hbiim)][CdCl4]center dot 2H(2)O (1), [Co(phen)(2)(Hbiim)][CdBr4]center dot 1.5H(2)O (2) and [Co(phen)(2)Hbiim][Cdl(4)]center dot C3H6O center dot 0.5H(2)O (3) (where phen = 1,10-phenanthroline and Hbiim = mono-anionic 2,2'-biimidazole). The complex salts 1-3 have been characterized by elemental analyses, spectroscopic techniques (UV-Vis, FT-IR and NMR) solubility product and conductivity measurements. Thermal behaviors and single crystal X-ray structure determination of the complex salts 1-3 are also discussed. The complex salts 1 and 2 are isomorphous and crystallize in space group P1, while 3 crystallizes in the monoclinic crystal system with the space group Pc. The two crystallographically different complex cations in 3 correspond to Lambda and Delta optical isomers. The crystals of 1 and 2 are centrosymmetric and so both isomers cohabit in the solid state as a racemate. The spatial disposition of the cations in the three complex salts, derived from the existence of the optical isomers, favours the formation of hydrogen bonding, as revealed by the presence of a R-2(2)(10) ring motif. The packing analyses of complex salts 1 and 2 shows the presence of open channels in which solvent molecules of crystallization are residing, while in 3 an ABCABC...type layered packing arrangement of constituents has been observed. Non-covalent interactions like C-H center dot center dot center dot X(Cl/Br/I), C-H center dot center dot center dot O (second sphere interactions) and O-H center dot center dot center dot O (water) play a key role in the stabilization of the crystal lattices. (C) 2011 Elsevier Ltd. All rights reserved.



subject category

Chemistry; Crystallography


Sharma, RP; Singh, A; Brandao, P; Felix, V; Venugopalan, P

our authors


The authors gratefully acknowledge the financial support of CSIR vide Grant No. 09/135/0594/2010/EMR-1.

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