Spectroscopic and computational studies of a series of high-spin Ni(II) thiolate complexes.
The electronic structures of a series of high-spin Ni(II)-thiolate complexes of the form [PhTt(tBu)]Ni(SR) (R = CPh(3), 2; C(6)F(5), 3; C(6)H(5), 4; PhTt(tBu) = phenyltris((tert-butylthio)methyl)borate) have been characterized using a combined spectroscopic and computational approach. Resonance Raman (rR) spectroscopic data reveal that the nu(Ni-SR) vibrational feature occurs between 404 and 436 cm(-1) in these species. The corresponding rR excitation profiles display a striking de-enhancement behavior because of 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 approximately 18,000 cm(-1) in all three complexes, is assigned as a thiolate-to-Ni CT transition involving molecular orbitals that are of pi-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.
Van Heuvelen
Katherine M
KM
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Cho
Jaeheung
J
Dingee
Timothy
T
Riordan
Charles G
CG
Brunold
Thomas C
TC
D056831:Coordination Complexes / Q000737:chemistry*; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry*; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman; D013438:Sulfhydryl Compounds / Q000737:chemistry*
D056831:Coordination Complexes; D013438:Sulfhydryl Compounds; D009532:Nickel