The Electronic Structures of Bis(cis-1,2-dicyano-1,2-ethenedithiolato)nickel Complexes

Abstract

The core binding energies of N1s and S2s in cis-1,2-dicyano-1,2-ethanedithiolate (maleonitriledithiolate, mnt) complexes were measured by means of X-ray photoelectron spectroscopy (XPS), and the energy differences between N1s and S2s, ΔE, were found to be 171.7–172.6 eV throughout the complexes studied. The lowest ΔE value, 171.7 eV, was shown by [Ni(mnt)2]−. The electronic structures of [Ni(mnt)2]− and [Ni(mnt)2]2− were calculated by the discrete variational Xα method. The XPS measurements and the molecular orbital (MO) calculations provide consistent results that the oxidation state of the nickel atom is +2 for both nickel mnt complexes and that the highest occupied MO is 5b3g, which is mainly localized on ligands and which holds an unpaired electron in [Ni(mnt)2]−.

The Electronic Structure and Spectroscopy of Metallo‐Dithiolene Complexes

“…These studies were important, in that they were able to quantify the extent of spin delocalization onto the olefinic carbon atoms. 1À is localized on the olefinic C atoms, which is in reasonable agreement with that predicted from Xa calculations (355). The remaining spin density delocalized onto the ligand periphery is dominantly on the cyano N (4%) with the cyano carbon possessing $1% of the unpaired spin density.…”

“…It is comforting to note that the results of extended Hückel, Xa, and DFT calculations support the experimental results, in that the bulk of the spin density is localized on the NiS 4 core, with the majority located on the four S atoms of the two mnt 2À ligands (355,381). The large sulfur contribution to the b 2g (381).…”

“…The large sulfur contribution to the b 2g (381). c Xa Spin densities are from Sano et al (355). The EHMO and BLYP calculations are described in (381).…”

Ab initio MO calculations for hexacyano complexes

“…These tendencies are also consistent with our DVresults, although the DVcalculation gave less negative carbon charges (0.17-to 0.04-) and more negative nitrogen charges (0.53-to 0.60-). 16 In the cyano complexes of Fe3+ and Fe2+, the calculated metal charges are 1.662+ and 1.379+, respectively; the difference is much smaller than the difference in the oxidation number. The 3d<r population for Fe3+ (0.962) is greater than that for Fe2+ (0.628), while the difference between the formal number of 3dx electrons and the calculated population of the 3dx orbital is greater in the Fe2+ complex (6.0 -5.662 = 0.338) than in the Fe3+ complex (5.0 -4.907 = 0.093).…”

Wavelength dependence of the photo-induced conversion of the Ni–C to the Ni–L redox state in the [NiFe] hydrogenase of Desulfovibrio vulgaris Miyazaki F

“…The exact nature of the latter is still disputed, but may correspond to a transition involving ligand orbitals. 32 Although Ni(mnt) 2…”