Triphenylantimony(V) Catecholates Based on 3,6-Di-tert-Butyl-2,5-Dihydroxy-1,4-Benzoquinone

• Published in: Russian journal of coordination chemistry Vol. 46; no. 6; pp. 386 - 393
• Main Authors: Okhlopkova, L. S., Poddel’sky, A. I., Smolyaninov, I. V., Fukin, G. K.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.06.2020; Springer Nature B.V
• Subjects: Antimony; Benzoquinone; Chemical reduction; Chemistry; Chemistry and Materials Science; Dichloromethane; Inorganic Chemistry; Molecular structure; Organometallic compounds; Physical Chemistry; Quinones; Toluene; Triethylamine; benzoquinone; antimony; cyclic voltammetry; redox-active ligand; diolate; catecholate; X-ray diffraction analysis
• ISSN: 1070-3284; 1608-3318
• DOI: 10.1134/S107032842005005X

2,5-Dihydroxy-3,6-di- tert -butyl- p -benzoquinone (Q t Bu Diol) reacts with Ph 3 SbBr 2 in toluene in the presence of triethylamine to yield the ionic complex [Et 3 NH] + [(Dione t Bu Diolate)SbPh 3 Br] – ( I ). The same reaction in methanol leads to complete displacement of bromide ions from the antimony coordination sphere and gives triphenylantimony(V) 1,2-diolate (Dione t Bu Diolate)SbPh 3 · MeOH ( II · MeOH). The molecular structure of the complexes was determined by X-ray diffraction (CIF files CCDC no. 1960681 ( I · toluene) and 1960682 ( II · 2MeOH)). Both complexes are characterized by quinoid bond distribution in the six-membered carbon rings and by C=O double bonds in the Ph 3 SbO 2 C 6 ( t- Bu) 2 O 2 moieties. Formally, the complexes can be considered as 3,6-di- tert -butyl- o -benzoquinone derivatives with the organometallic Ph 3 SbO 2 group in positions 4 and 5 of the quinone ring. The electrochemical reduction of II · MeOH in dichloromethane occurs at E 1/2 = –1.52 V, which is significantly shifted to the cathodic region relative to the data for 3,6-di- tert -butyl- o -benzoquinone ( E 1/2 = –0.51 V). This redox potential shift indicates a significant decrease in the electron-withdrawing properties of the o -quinoid moiety, which is caused by the effect of the electron-donating catecholate metallacycle.