Synthesis, chemical characterization, structural data and solid state behaviour of N, N′-diethyl-1, 2-ethanediamine complexes of nickel (II) thiocyanate

Abstract

[NiL₂(NCS) ₂]•H₂O (1) and [NiL₂(NCS) ₂] (2) (L = N, N′-diethyl-1, 2-ethanediamine) have been synthesized from solution. The species 1 on deaquation transforms to [NiL₂(NCS) ₂] (1a) which subsequently undergoes an irreversible exothermic phase transition (118–142°C; ΔH = −3.8kJ mol⁻¹) accompanied by a pinkish-blue to blue thermochromism producing an isomer [NiL₂(NCS) ₂] (1b). The pinkish-blue species 2 on heating shows an endotherm (82–120°C; ΔH = kJ mol⁻¹) yielding the species 1b. Single crystal X-ray structure analyses of 1 and 2 have been carried out. The metal atoms in both the complexes, lying at crystallographic inversion centres, display distored octahedral geometries with four amine nitrogen atoms defining the equatorial plane and two isothiocyanato groups in trans axial positions.