Synthesis and spectroscopic characterization of Ni(II) complexes involving functionalised dithiocarbamates and triphenylphosphine: Anagostic interaction in (N-cyclopropyl-N-(4-fluorobenzyl) dithiocarbamato-5,5′) (thiocyanato-N)(triphenylphosphine)nickel(II)

Twelve new nickel(II) complexes namely [Ni(S2CNRR')(2)](1-6) and [Ni(S2CNRR')(NCS)(PPh3)](7-12) [where R = cyclopropyl (Pr-c); R' = 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- (6,11), 4Cl-C6H4-CH2- (6,12)] have been prepared and characterized by elemental analysis, IR, UV-Vis and NMR (H-1 and C-13) spectroscopy. A single crystal X-ray structural analysis was carried out for (N-cyclopropyl-N-(4-fluorobenzyl)dithiocarbamato-S,S')(thiocyanato-N)- (triphenylphosphine)nickel(II). The increase in wavenumber of v(C-N) thioureide and decrease in chemical shift values of heteroleptic complexes 7-12 compared to that of homoleptic complexes 1-6 are due to the mesomeric drift of electron density from the dithiocarbamate moiety towards the metal centre, increasing the carbon nitrogen double bond character. The increased strength of C-N bond is due to the presence of the pi-accepting triphenylphosphine. Electronic spectral studies indicated square planar geometry around the nickel(II) central atom for all the complexes. Single crystal X-ray structural analysis of 11 confirms that the coordination geometry about the Ni is distorted square planar. The C-H center dot center dot center dot F interactions lead to a polymeric structure and a rare intramolecular anagostic interaction [M center dot center dot center dot H = 2.929 angstrom] is observed. The molecular geometry, HOMO-LUMO in the ground state and MEP have been calculated for 11 using the Hartree-Fock (HF) method with the LANL2DZ basic set. The optimized bond lengths and bond angles agree well with the experimental results. The asymmetry in the Ni-S bonds reveal the greater trans influence of triphenylphosphine compared to that of the isothiocyanate ion. (C) 2015 Elsevier B.V. All rights reserved.