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

•Twelve new Ni(II)-functionalized dithiocarbamate complexes were synthesized.•X-ray crystal structural analysis revealed the trans effect of PPh3 on Ni–S bonds.•Anagostic (C–H⋯Ni) and C–H⋯π(chelate) interactions are observed.•Trans effect of triphenylphosphine is absent in gaseous state.

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), 4CH3O–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 (1H and 13C) spectroscopy. In the case of heteroleptic complexes 7–12, the shift in vC-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 vC-N bond due to the presence of π-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⋯Ni intramolecular anagostic interaction. C–H⋯π (chelate) is observed in complexes 10. Supramolecular frame works are stabilised by C–H⋯S, C–H⋯π and C–H⋯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.

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