Synthesis, spectral, structural and computational studies on NiS4 and NiS2NP chromophores: Anagostic and C-H center dot center dot center dot pi (chelate) interactions in [Ni(dtc)(PPh3)(NCS)] (dtc = N-(2-phenylethyl)-N-(4-methoxybenzyl)- dithiocarbamate and N-(2-phenylethyl)-N-(4-chlorobenzyl)dithiocarbamate)

摘要

Bis(N-(2-phenylethyl)-N-substituted benzyldithiocarbamato-S,S')nickel(II) (1-6) and (N-(2-phenylethyl)-N-substituted benzyldithiocarbamato-S,S')(thiocyanato-N) (triphenylphosphine)nickel(II) (7-12) [substituted benzyl = 2HO-C6H4-CH2- (1,7), 3HO-C6H4-CH2- (2,8), 4HO-C6H4-CH2- (3,9), 4CH(3)O-C6H4-CH2- (4,10), 4F-C6H4-CH2- (5,11), 4Cl-C6H4-CH2- (6,12)] complexes have been synthesized and characterized by elemental analysis, IR, UV-Vis and NMR (H-1 and C-13) spectroscopy. In the case of heteroleptic complexes 7-12, the shift in v(C-N) values to higher wavenumber and the NCS2 carbon signals are shifted to downfield compared to the homoleptic complexes indicating the increasing strength of thioureide v(C-N) bond due to the presence of pi-accepting triphenylphosphine ligand in heteroleptic complexes. Electronic spectral studies on all the complexes (1-12) suggest square planar geometry around the nickel(II). Structures of 10 and 12 have been elucidated by X-ray crystallography. The dithiocarbamate anions in 10 and 12 chelate to the nickel atom. Both the structures reveal C-H center dot center dot center dot Ni intramolecular anagostic interaction. C-H center dot center dot center dot pi (chelate) is observed in complexes 10. Supramolecular frame works are stabilised by C-H center dot center dot center dot S, C-H center dot center dot center dot pi and C-H center dot center dot center dot Cl non-covalent interaction. The molecular geometry, HOMO-LUMO in the ground state and MEP have been calculated for 10 and 12 using Hartree-Fock (HF) method with LANL2DZ basic set. Molecular electrostatic potential diagram of complexes 10 and 12 support the partial double bond character of C-N (thioureide) bond in dithiocarbamate ligands. (C) 2016 Elsevier B.V. All rights reserved.