Synthesis, crystal structure, thermal and theoretical studies of bis(N-ethyl-N-phenyldithiocarbamato) Ni(II) and (N-ethyl-N-phenyldithiocarbamato) (isothiocyanato) (triphenylphosphine) Ni(II)

Abstract

Homoleptic and heteroleptic Ni(II) complexes represented as NiL12 and NiL1L2L3 (where, L1 = N-ethyl-N-phenyldithiocarbamato anion, L2= isothiocyanato anion, and L3 = triphenylphosphine) were synthesized. The complexes have been characterized by elemental, IR, NMR, and single-crystal X-ray analysis. The thermal decomposition behaviour of the complexes were studied using thermogravimetric analysis (TGA). The optimized geometry and the electronic analysis of the type of bonding within the complex structures were performed using methods based on the density functional theory and atom in molecule (AIM) analysis method. X-ray structural analysis of both complexes confirms distorted square planar geometry about the Ni atom. The TGA indicates that the complexes belong to the class of volatile dithiocarbamates which yield the corresponding metal sulphide without any intermediate products. Structural parameters from crystallographic and DFT studies have been compared and found to correlate with each other. The small discrepancies in geometric parameters are attributable to H-bonding and packing interactions within the lattice which are not modelled during computational study. AIM analysis suggests that in NiL1L2L3, the Ni ⋯L interactions are more covalent in nature whereas in NiL12 complex, they are more ionic in character.