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

• Nikolay O. Chalkov,
• Vladimir K. Cherkasov,
• Gleb A. Abakumov,
• Andrey G. Starikov and
• Viacheslav A. Kuropatov

Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238

• ; EPR spectroscopy; extended tetrathiafulvalene; protonated semiquinone; Introduction The main idea that led to the creation of the system constructed of two o-quinone terminal moieties bridged with annulated extended tetrathiafulvalene (TTF) insertion, was an attempt to explore acceptor–donor–acceptor

• products [4][5][6]. This leads to the fact that the EPR signal related to a protonated semiquinone species is often quite weak or even undetectable. In the spectrum, two separate triplet splittings of 2.52 and 1.26 G are attributable to the hyperfine interaction with protons of the central p-phenylene ring

• is largely determined by the configuration of the surrounding coordination sites at the termini of the molecule. Thus, (1.)H or (1.)H3, contain a protonated semiquinone at the one side and an o-quinone or catechol on the opposite side, respectively. As a result there is a non-symmetric spin-density