| 20199095 |
Van Heuvelen KM, Kieber-Emmons MT, Riordan CG, Brunold TC: Spectroscopic and computational studies of a trans-mu-1,2-disulfido-bridged dinickel species, [{(tmc) Ni}(2)(S (2))](OTf)(2): comparison of end-on disulfido and peroxo bonding in (Ni (II))(2) and (Cu (II))(2) species. Inorg Chem. 2010 Apr 5;49(7):3104-12.
A powerful means of enhancing our understanding of the structures and functions of enzymes that contain nickel-sulfur bonds, such as Ni superoxide dismutase, acetyl-coenzyme A synthase/carbon monoxide dehydrogenase, [NiFe] hydrogenase, and methyl-CoM reductase, involves the investigation of model compounds with similar structural and/or electronic properties. In this study, we have characterized a trans-mu-1,2-disulfido-bridged dinickel (II) species, [{(tmc) Ni}(2)(S (2))](2+) (1, tmc = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) by using electronic absorption, magnetic circular dichroism (MCD), and resonance Raman (rR) spectroscopic techniques, as well as density functional theory (DFT) and time-dependent DFT computational methods. Our computational results, validated on the basis of the experimental MCD data and previously reported (1) H NMR spectra, reveal that 1 is best described as containing two antiferromagnetically coupled high-spin Ni (II) centers. A normal coordinate analysis of the rR vibrational data was performed to quantify the core bond strengths, yielding force constants of k (Ni-S) = 2.69 mdyn/A and k (S-S) = 2.40 mdyn/A. These values provide a useful basis for a comparison of metal-S/O bonding in 1 and related Ni (2)(O (2)), Cu (2)(O (2)), and Cu (2)(S (2)) dimers. In both the disulfido and the peroxo species, the lower effective nuclear charge of Ni (II) as compared to Cu (II) results in a decreased covalency, and thus relatively weaker metal-S/O bonding interactions in the Ni (2) dimers than in the Cu (2) complexes. |
31(0,1,1,1) |