Effect of N-Bound Organic Moiety in Dithiocarbamate (R₂NCS⁻₂) and trans Influence of Triphenylphosphine on NiS₂PN Chromophore

GRAPHICAL ABSTRACT

Abstract

Three square planar Ni(II) complexes of the composition [Ni(bzcprdtc)₂](1), [Ni(bzcprdtc)(NCS)(PPh₃)](2) and [Ni(bzcprdtc)(PPh₃)₂]ClO₄ (3)[(where bzcprdtc = N-benzyl-N-cyclopropyl-dithiocarbamate)] have been synthesized and characterized by ¹H and ¹³C NMR, UV-Vis and FT-IR spectroscopy. ¹³C NMR spectra show interesting differences between the N¹³CS₂ carbon signals of the parent complex 1 and heteroleptic complex 2. The N¹³CS₂ carbon signal for 2 is observed at 209.3 ppm with an upfield shift of about 3.5 ppm compared with that found for 1 (212.8 ppm). The observed shielding in 2 indicates the effect of PPh₃ on the mesomeric drift of electron density toward nickel through the thioureide C‒N bond of [Ni(dtc)(NCS)(PPh₃)]. Single crystal X-ray analysis of 2 and [Ni(dbpdtc)(NCS)(PPh₃)](4) (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate) confirmed distorted square planar arrangement in the vicinity of the nickel atom with a S₂NP donor set. Comparative analysis of bond parameters of [Ni(dtc)₂] and [Ni(dtc)(NCS)(PPh₃)] has also been studied.

Keywords:

• Dithiocarbamate
• nickel(II)
• thiocyanate
• single-crystal X-ray analysis