C-H•••Ni and C-H•••π(chelate) interactions in nickel(II) complexes involving functionalized dithiocarbamates and triphenylphosphine

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-C6H4-CH2- (1,4), 3-HO-C6H4-CH2- (2,5), 4-F-C6H4-CH2- (3,6)] were synthesized and characterized using IR, electronic, and NMR (H-1 and C-13) 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 NiS4 and NiS2PN chromophores, respectively. The v(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 ((NCS2)-C-13) 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 center dot center dot center dot pi(chelate) interactions results in polymeric chain. Both structures show intramolecular Ni center dot center dot center dot H interactions but that on 6 is the strongest. C-H center dot center dot center dot pi 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. (C) 2018 Elsevier B.V. All rights reserved.