Synthesis, spectral and antibacterial studies on Ni(II) and Zn(II) complexes involving N-furfuryl-N-isopropyldithiocarbamate (f iprdtc) and Lewis bases: X-ray structure of [Ni(f iprdtc)(NCS)(PPh3)

Abstract

[Ni(fiprdtc)2] (1), [Ni(fiprdtc)(PPh3)(NCS)] (2), [Ni(fiprdtc)(PPh3)2]ClO4 (3), [Zn(fiprdtc)2] (4), [Zn(fiprdtc)2(1,10-phen)] (5) and [Zn(fiprdtc)2(2,2′-bipy)] (6) (f iprdtc=N-furfuryl-N-isopropyldithio- carbamate, 1,10-phen=1,10-phenanthroline and 2,2′-bipy=2,2′-bipyridine) complexes were prepared and characterized by elemental analysis, electronic, IR and NMR spectra and the structure of 2 was determined by single-crystal X-ray crystallography. UV–Vis spectral data of 1–3 are consistent with the formation of square planar complexes. IR spectra of the complexes show the contribution of the thioureide form to the structure. A single-crystal X-ray structural analysis of 2 proved four-coordinated nickel in a distorted square planar arrangement with a S2PN donor set. Significant asymmetry in Ni–S bond distances was observed in [Ni‒ S1=2.1655(8); Ni‒ S2=2.2120(8) Å]. This observation clearly supports the less effective trans of SCN− over PPh3. The observed shielding in N13CS2 chemical shifts of heteroleptic nickel complexes 2 and 3 when compared with homoleptic nickel complex 1 indicates the effect of PPh3 on the mesomeric drift of electron density toward nickel through the thioureide C‒ N bond. The N13CS2 chemical shift of 5 and 6 are additionally deshielded compared with 4 owing to the increase in coordination number. Complexes were screened for in vitro antibacterial activity and significant activity has been found.