Double Oxidative Dehalogenation of 2,5-Bis(diisopropylphosphoryl)-3,6-difluoro-1,4-hydroquinone leading to Formation of New Copper Quinonoid Complexes

Paul D. Entzminger
Natalie C. Cawker
Amanda N. Graveson
Alexander N. Erikson
Eugenijus Urnezius, University of Portland
Edward J. Valente, University of Portland

Zeitschrift für anorganische und allgemeine Chemie, 2015, Volume 641, Issue 2, 414-420.

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Linked version is final published version.

Abstract

Open air reactions of 2,5-bis(diisopropylphosphoryl)-3,6-difluoro-1,4-hydroquinone with (bipy)Cu(CH3COO)2 or (bipy)CuCl2 in wet methanol proceeded with oxidative dehalogenation of the ligand and the formation of bimetallic complexes supported by 2,5-bis(diisopropylphosphoryl)-3,6-dioxy-1,4-quinonate. The coordination mode of the bridging ligand towards (bipy)Cu(X) fragments depends on the nature of the anionic ligand (X = acetate or chloride). Thus, in bimetallic complex 2 [bis((2,2′-bipyridyl)copper(η2-acetate))-μ-(η2(O,O)-2,5-bis(diisopropylphosphoryl)-3,6-dioxy-1,4-quinonate] the ligand coordinates two (bipy)Cu(acetate) fragments into the [O,O] chelation pockets of the tetraoxolene core. In bimetallic complex 3 [bis((2,2′-bipyridyl)copper(chloride))-μ-(η2(O,(P=O))-2,5-bis(diisopropylphosphoryl)-3,6-dioxy-1,4-quinonate] the ligand coordinates the (bipy)CuCl fragments into its [O,(P=O)] pockets. Coordination chemistry was briefly explored by subjecting complex 3 to ligand-substitution reactions by reacting it with AgBF4 and with carboxylate and carbonate salts. Complexes 4 [bis((aqua)(dimethylformamide)(2,2′-bipyridyl)copper)-μ-(η2(O,(P=O))-2,5-bis(diisopropylphosphoryl)-3,6-dioxy-1,4-quinonate) di-tetrafluoroborate] and 5 [bis(aqua)(2,2'-bipyridyl)copper-(η2(O,O)-3,6-bis(diisopropylphosphoryl)-4,5-dioxy-1,2-quinonate] were obtained during these investigations. Compounds 25 were characterized by single-crystal X-ray diffraction, elemental analyses, and by spectroscopic and magnetic measurements.