Viacheslav A. Kuropatov

Sterically Hindered o-Quinone Annulated with Dithiete: A Molecule Comprising Diolate and Dithiolate Coordination Sites

A new stable sterically hindered o-quinone annelated with a 1,2-dithiete ring was prepared by using mild conditions. The skeleton of the compound comprises diolate and dithiolate functions that have the potential to bind metals leading to the corresponding complexes. The reactivity of this compound as a ligand with respect to both coordination sites was studied. Reactions with metals indicate that the o-quinone function is reduced in the first stage to give semiquinonate and catecholate complexes. The dithiolate coordination site was involved in the reaction in a few cases only after diolate was bound. A trinuclear manganese complex with coordination on both sites was obtained and characterized by EPR spectroscopy. The electrochemical study of this quinone fused with dithiete is reported.

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

The chemical oxidation and reduction processes of deprotonated, direduced o-quinone-exTTF-o-quinone in protic solvents were studied by EPR spectroscopy. The formation of relatively stable paramagnetic protonated redox forms of the parent triad was very surprising. The character of spin-density distribution in the semiquinone–quinone and semiquinone–catechol redox forms indicates that the p-phenylene-extended tetrathiafulvalene connector provides a quite effective electronic communication channel between dioxolene coordination sites. It was found that the deprotonated, direduced o-quinone-exTTF-o-quinone is capable to reduction of the metal copper in solution. The radical anion species formed in this reaction exists in solution as a solvent-separated ion pair with a copper cation. A character of spin-density distribution in a radical anion species leads to the conclusion that the ligand corresponds to type III of the Robin–Day classification.

EPR spectroscopy study of di-o-quinone bridged by π-extended TTF: redox behavior and binding modes as a ligand

The peculiarities of the spin density distribution in the radical-anion form of an acceptor–donor–acceptor (A–D–A) system, consisting of two sterically hindered o-quinone moieties bridged by a p-phenylene extended tetrathiafulvalene molecule, was studied. It was chemically reduced with alkali metals. The reduction proceeds through four one-electron stages. The radical-anion and radical-trianion species are paramagnetic, whereas the dianion form was found to be EPR silent. The spin density distribution in the paramagnetic forms was studied. EPR and UV-vis spectra analyses and DFT calculations reveal that the p-phenylene extended TTF fragment in the ligand in all of the studied redox forms acts as a conducting bridge that provides electronic communication between the two o-quinone moieties.

Crystalline complexes of fullerene with anisole derivatives

For the first time, bis(anisole)chromium fulleride (PhOMe)2Cr+·[C60]−· and a crystalline complex of fullerene with ortho-butoxyanisole have been obtained. The temperature dependence of the parameters of the EPR spectrum of bis(anisole)chromium fulleride (PhOMe)2Cr+·[C60]−· has been studied. The molecular structure of the complex of fullerene with ortho-butoxyanisole has been established.