The electronic structures of a series of high-spin Ni(II)-thiolate complexes of the form [PhTttBu]Ni(SR) (R = CPh3, 2; C6F5, 3; C6H5, 4; PhTttBu = phenyltris((tert-butylthio)methyl)borate) have been characterized using a combined spectroscopic and computational approach. Resonance Raman (rR) spectroscopic data reveal that the νNi–SR vibrational feature occurs between 404 and 436 cm−1 in these species. The corresponding rR excitation profiles display a striking de-enhancement behavior due to interference effects involving energetically proximate electronic excited states. These data were analyzed in the framework of time-dependent Heller theory to obtain quantitative insight into excited state nuclear distortions. The electronic absorption and magnetic circular dichroism spectra of 2 – 4 are characterized by numerous charge transfer (CT) transitions. The dominant absorption feature, which occurs at ~18,000 cm−1 in all three complexes, is assigned as a thiolate-to-Ni CT transition involving molecular orbitals that are of π-symmetry with respect to the Ni–S bond, reminiscent of the characteristic absorption feature of blue copper proteins. Density functional theory computational data provide molecular orbital descriptions for 2 – 4 and allow for detailed assignments of the key spectral features. A comparison of the results obtained in this study to those reported for similar Ni-thiolate species reveals that the supporting ligand plays a secondary role in determining the spectroscopic properties, as the electronic structure is primarily determined by the metal–thiolate bonding interaction.