Synthesis, molecular and crystalline architectures, and properties of a mononuclear complex [Co II (benzidine) 2 (NCS) 2 (OH 2 ) 2

Abstract

One mononuclear cobalt(II) compound of the type [Co(bnzd)2(NCS)2(OH2)2] (1) (bnzd = benzidine) has been isolated through a single-pot reaction of the molecular building components in MeOH–H2O solvent mixture at room temperature and characterized by physico-chemical and spectroscopic methods. The crystal structure of complex 1 has an octahedral geometry with trans, trans, trans orientations in the order (Na,Na), (Nt,Nt), (Ow,Ow) [Na = N(amine), Nt = N(thiocyanate) and Ow = O(water)]. In crystalline state, individual units of 1 are associated by weak cooperative O–H...N, O–H...S and N–H...S hydrogen bonds resulting in a 3D network structure. The compound is redox active and shows luminescence in MeOH solution. Thermal decomposition pattern of 1 reveals the presence of two coordinated water molecules. Variable-temperature magnetic susceptibility measurement shows significant orbital contribution and numerical matrix diagonalization method gives the best fit parameters: α = A*k = 1.43; λ = −130 cm − 1; Δ = − 864 cm − 1; TIP = 0.000975; R = 1.19 × 10 − 4. Mononuclear compound [Co(benzidine)2(NCS)2(OH2)2] (1) was isolated and characterized. Cobalt(II) center adopts an octahedral geometry and individual units of 1 are associated by weak O–H…N/S and N–H…S hydrogen bonds resulting in a 3D network structure. Complex 1 is electroactive and shows luminescence property. Variable-temperature magnetic property shows significant orbital contribution.