Quantitative softness values and structure of Co[Ag(SeCN)2]2 and its complexes

Abstract Co[Ag(SeCN) 2 ] 2 and its complexes with different ligands have been synthesized. Dimethylformamide, dimethylsulphoxide, tetrahydrofuran, dioxan and aniline form polymeric chain complexes of general formula >(L) 2 Co[Ag(SeCN) 2 ] 2 6 ][Ag(SeCN) 2 ] 2 . α-Picoline, aminopyridines and 2-aminopyrimidine also form cationic—anionic complexes but the cobalt in these complexes is in a tetrahedral coordination geometry and the suggested formula is [CoL 4 ][Ag(SeCN) 2 ] 2 . Structures are proposed on the basis of IR and electronic spectral and magnetic moment and conductance studies. Quantitative values of softness, E ≠ n , of Co(II) and Ag(I) and E ≠ m of the —NCSe and —SeCN and various ligands (L) are calculated. Based on the HSAB principle, the E ≠ n and E ≠ m values are applied to extend support to the proposed structures of the complexes in a novel manner.