Molecular and Electronic Structures of Oxo-bis(benzene-1,2-dithiolato)chromate(V) Monoanions. A Combined Experimental and Density Functional Study

Abstract

Two oxo-bis(benzene-1,2-dithiolato)chromate(V) complexes, namely, [CrO(L(Bu))2]1- and [CrO(L(Me))2]1-, have been synthesized and studied by UV-vis, EPR, magnetic circular dichroism (MCD), and X-ray absorption spectroscopy and by X-ray crystallography; their electro- and magnetochemistries are reported. H2L(Bu) represents the pro-ligand 3,5-di-tert-butylbenzene-1,2-dithiol, and H2L(Me) is the corresponding 4-methyl-benzene-1,2-dithiol. A structural feature of interest for both the complexes is the folding of the dithiolate ligands about the S-S vector providing Cs symmetry to the complexes. Geometry optimizations using all-electron density functional theory with scalar relativistic corrections at the second-order Douglas-Kroll-Hess (DKH2) and zeroth-order regular approximation (ZORA) levels result in excellent agreement with the experimentally determined structures and electronic and S K-edge X-ray absorption spectra. From DFT calculations, the Cs instead of C2v symmetry for the complexes is attributed to the strong S(3p) --> Cr(3d(x2-y2)) pi-donation in Cs geometry providing additional stability to the complexes.

Is the spin‐orbit coupling important in the prediction of the 51V hyperfine coupling constants of VIVO2+ species? ORCA versus Gaussian performance and biological applications

“…However, a significant negative spin population (between −0.15 and −0.28) is expected on the terminal oxido donor. A negative spin density on such terminal ligands has been found also in [Cr V O(benzene‐1,2‐dithiolato) 2 ] 2− [ 53 ] and suggested for [Mo 17 O(PhS) 4 ] − on the basis of the experimentally measured hyperfine and nuclear quadrupole interaction parameters for the oxido‐ 17 O. [ 54 ] It has been postulated that the negative spin density may originate from spin‐polarization mechanisms.…”

Exploring the limits of redox non-innocence: pseudo square planar [{κ4-Me2C(CH2NCHpy)2}Ni]n (n = 2+, 1+, 0, −1, −2) favor Ni(ii)

“…48 In part, the conception of radical character in Ni[+], Ni[0] and Ni[À] derives from the successful implementation of DFT and ab initio calculations in assessing the energies and EPR spectra of the complexes. 3,[52][53][54][55][56][57][58][59] Corresponding valence bond (VB) depictions (see Schemes) in which a radical is portrayed can be construed as suggestive of radical chemistry, yet there is little or no corresponding reactivity. Persistent organic radicals oen do not display signicant reactivity, and it appears that radical character inferred from DFT interpretations of weak metal-ligand interactions may be similarly categorized.…”

Multireference ab initio studies of zero-field splitting and magnetic circular dichroism spectra of tetrahedral Co(ii) complexes

“…Both formulations of the theory have found widespread use in the MCD community. [31][32][33][35][36][37][38][39][40][41][42][43] MCD spectra of high spin Co(II) complexes have attracted inorganic chemists due to the strongly featured absorption spectra of this ion. 3,23,44-49 Co(II) is frequently used as a substitute for Zn(II) since the latter cannot be probed by EPR.…”