1,4-Bis(phosphine)-2,5-difluoro-3,6-dihydroxybenzenes and their P-oxides: Syntheses, structures, ligating and electronic properties

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Reactions of 1,4-difluoro-2,5-dimethoxybenzene with LDA (1:2) at low temperatures generated organodilithio intermediates; quenching the reaction mixtures with chlorophosphines ClPR2 produced 1,4-bis(phosphino)-2,5-difluoro-3,6-dimethoxybenzenes 1a (R = Ph) and 1b (R = iPr). Demethylation of 1a-b was accomplished by BBr3, yielding bis(phosphino)hydroquinones 2a-b. Treating 2a-b with excess hydrogen peroxide produced bis(phosphinyl)hydroquinones 3a-b. The binucleating properties of 2a were established by the formation of a bimetallic nickel complex upon reaction with Ph2Ni(PMe3)2. Electrochemical activity of hydroquinones 2a-b and 3a-b was examined by cyclic voltammetry. In addition, compounds 2a, 3a and 3b were obtained in crystalline form and characterized by single-crystal X-ray diffraction. The influence of the fluorine substituents on the composition of the frontier orbitals of 2a and 3a was examined by computational methods. © 2008 Elsevier B.V. All rights reserved.

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Journal of Organometallic Chemistry