Synthesis, X-ray structure and molecular properties of a new cobalt(III) complex of the type [Co(L)(SCN)2 ]ClO4 [L = N,N'-(bis(pyridin-2-yl)benzylidene)-1,2-ethanediamine]

Department of Chemistry, Kabi Nazrul College, Murarai, Birbhum-731 219, West Bengal, India E-mail : habibar_hs@yahoo.co.in Department of Chemistry, MUC Women’s College, Burdwan-713 104, West Bengal, India Manuscript received online 07 December 2016, accepted 09 December 2016 One new hexacoordinated cobalt(III)isothiocyanato complex of the type [Co(L)(SCN)2 ]ClO4 (1) [L = N,N'- (bis(pyridin-2-yl)benzylidene)-1,2-ethanediamine] is isolated using a 1 : 1 : 2 molar ratio of Co(ClO4 )2 .6H2O, L and NH4NCS in a methanolic solvent at room temperature. The compound 1 has been characterized using microanalytical, spectroscopic, X-ray crystallographic and other physicochemical results. Structure of [Co(L)(SCN)2 ]ClO4 (1) is solved by X-ray diffraction measurements. 1 crystallizes in the monoclinic space group C2/c. Some crystal data are : a = 12.3151(3) Å, b = 12.7842(3) Å, c = 18.7199(5) Å, ß = 99.365(2)o and Z = 4. Cobalt(III) center in 1 has a distorted octahedral coordination environment with a CoN4 S2 chromophore ligated by four N atoms of the tetradentate Schiff base and two S atoms of S-coordinated SCN– ions mutually in trans orientation. The mononuclear units in 1 are engaged in weak cooperative intermolecular C-H···N and C-H···O hydrogen bonds and ·π··π interactions resulting cagelike 3D network structure. Room temperature solid-phase magnetic susceptibility measurement show that complex 1 is diamagnetic (t2g 6 , S = 0). In CV, a quasi-reversible one-electron reductive response due to cobalt(III)-cobalt(II) couple is observed in 1. Compound 1 displays intraligand 1(π-π*) fluorescence and intraligand 3(π-π*) phosphorescence in glassy solutions