G. A. Abakumov

Fluorinated 3,6-di-tert-butyl-o-benzoquinones

New fluorine- containing 3,6-di-tert-butyl-o-benzoquinones have been synthesized. In the EPR spectra the19F hyper fine coupling constant of the corresponding semiquinones was shown to be highly dependent on the metal, its surrounding ligand, and the solvent.

Coordination-sphere dynamics of bisphosphine o-semiquinone complexes of copper(I)

Depending on steric effects of phosphine and o-semiquinone (SQ) ligands bonded to the copper atom, (R3P)2CuSQ complexes have either pseudotetrahedral geometry with equivalent phosphine ligands or trigonal-pyramidal with one equatorial and one axial phosphine ligand. In an ESR study of the exchange dynamics of the phosphine ligands in trigonal-pyramidal complexes, the kinetic parameters of the exchange were determined. A model was proposed which explains distortions in the geometry of the complexes by nonvalence interatomic interactions on the “periphery” of the phosphine and SQ ligands.

An EPR and IR spectral study of paramagnetic cobalt dinitrosyl-o-semiquinone complexes

ConclusionsMixed paramagnetic cobalt dinitrosyl o-semiquinone complexes were obtained for the first time in solution. IR and EPR spectroscopy showed that these complexes have distorted tetrahedral structure, while their ground electronic state is [Co(NO)2]10 with the unpaired electron on the o-semiquinone ligand.

EPA spectra of13CO-labelled rhodium carbonyl o-benzosemiquinone complexes

Conclusions1.Analysis of the hyperfine structure in the EPR spectra of dicarbonyl semiquinone complexes served as the basis for evaluating the spin density of the unpaired electron localized predominantly in the semiquinone ligand.2.The coupling constant with the13C nucleus in CO for the SQ complexes is sensitive to the ligand environment but cannot be used for determining the position of the carbonyl ligand in the complex relative to SQ.