[Ni(4-mpipdtc)2] and [Ni(4-mpipdtc)(PPh3)(NCS)] (4-mpipdtc = 4-methylpiperidinecarbodithioate anion) have been characterized by electronic, IR, and NMR spectroscopy, single crystal X-ray analysis, and cyclic voltammetry. IR spectra of the complexes show the contribution of the thioureide form to the structures. 1H NMR spectra show the deshielding of α-CH2 protons on complexation. 13C NMR spectra shows interesting differences between the N13CS2 carbon signals of the parent complex [Ni(4-mpipdtc)2] and the mixed ligand complex [Ni(4-mpipdtc)(PPh3)(NCS)]. The N13CS2 carbon signal for [Ni(4-mpipdtc)(PPh3)(NCS)] is observed at 204.85 ppm with an upfield shift of about 3.8 ppm compared with that found in [Ni(4-mpipdtc)2] (201.06 ppm). The observed shielding in [Ni(4-mpipdtc)(PPh3)(NCS)] indicates the effect of PPh3 on the mesomeric drift of electron density toward nickel through the thioureide C–N bond. Single crystal X-ray analysis of [Ni(4-mpipdtc)2] and [Ni(4-mpipdtc)(PPh3)(NCS)] confirms the presence of four-coordinated nickel in a distorted square-planar arrangement with the NiS4 and NiS2PN chromophores, respectively. The C–N (thioureide) bond lengths of [Ni(4-mpipdtc)(PPh3)(NCS)] are shorter than those found in [Ni(4-mpipdtc)2], because of the presence of the π-acid (triphenylphosphine) in [Ni(4-mpipdtc)(PPh3)(NCS)]. Significant asymmetry in Ni–S bond distances was observed in Ni(4-mpipdtc)(PPh3)(NCS)] (2.162(2) and 2.211(2) Å). This observation clearly supports the less effective trans effect of SCN– over PPh3. The piperidine ring in the dithiocarbamate fragment is in the normal chair conformation.Graphical Abstract: