CH⋯Ni and CH⋯π(chelate) interactions in nickel(II) complexes involving functionalized dithiocarbamates and triphenylphosphine

Abstract New bis( N -benzyl- N -substituted benzyldithiocarbamato-S,S′)nickel(II) ( 1–3 ) and ( N -benzyl- N -substituted benzyldithiocarbamato-S,S′)(isothiocyanato- N )- (triphenylphosphane)nickel(II) ( 4–6 ) [where substituted benzyl = 2-HO C 6 H 4 CH 2 ( 1 , 4 ), 3-HO C 6 H 4 CH 2 ( 2 , 5 ), 4-F C 6 H 4 CH 2 ( 3 , 6 )] were synthesized and characterized using IR, electronic, and NMR ( 1 H and 13 C) spectra. X-ray structural analysis of homoleptic complex ( 1) and heteroleptic complexes ( 5 and 6) confirmed the presence of four coordinated nickel in a distorted square planar arrangement with NiS 4 and NiS 2 PN chromophores, respectively. The ν C–S stretching vibrations are observed around 990 cm −1 without any splitting supporting the bidentate coordination of the dithiocarbamate ligand. Electronic spectral studies of all the complexes ( 1 – 6 ) indicate that the geometry of the nickel atom is probably square planar. NMR spectra of all homoleptic and heteroleptic complexes ( 1–6 ) reveal a weak signal associated with the backbone carbon (N 13 CS 2 ) in the region 204.0–210.0 ppm with a weak intensity characteristic of the quaternary carbon signals. The greater trans influence of triphenylphosphine in complexes 5 and 6 is supported by the long Ni S distance compared to other Ni S distance which is opposite to the NCS − ligand. In the structure of complex 5 , C–H⋯π(chelate) interactions results in polymeric chain. Both structures show intramolecular Ni⋯H interactions but that on 6 is the strongest. C–H⋯π interactions are also found in 1 , 5 and 6 . Hirshfeld surface analysis and the associated 2D fingerprint plots of 1 , 5 and 6 have been studied to evaluate intermolecular interactions. The molecular geometries of complexes 1 , 5 and 6 have been optimized by abinitio HF method using LANL2DZ program.