title: Synthesis, X-ray Structure, and Electrochemical Oxidative Coupling Reactions of 1,5- and 2,6-Bis(1,4-dithiafulven-6-yl)naphthalenes.
abstract: Novel pi-extended tetrathiafulvalene (TTF) derivatives (12a-c, 13a-c, 15a-c) in which the two 1,3-dithiole units are connected through a naphthalene spacer have been prepared in high yields by Wittig-Horner olefination reaction from dialkoxy-substituted diformylnaphthalenes (11a,b, 14) and differently substituted phosphonate esters (10a-c). The electrochemical study revealed a similar behavior for the novel electron donor molecules (12a-c, 13a-c, 15a-c) regardless of the position of the 1,3-dithiole rings on the naphthalene core. The extended donors undergo an efficient electrooxidation process affording new oligomeric extended TTF species which exhibit lower oxidation potential values than their precursor donors. EPR experiments confirm the presence of the cation radical derived from the oligomeric TTF vinylogues and support an ECE process. The structural study has been carried out by X-ray analysis of 12a and semiempirical PM3 calculations and reveals a distorted geometry from the planarity with the naphthalene moiety forming an angle of approximately 35 degrees with the thiafulvalene rings. A good agreement was found between the experimental and calculated values, thus validating the PM3 method. The chemical oxidation of the synthesized donors (12a-c, 13a-c, 15a-c) with strong electron acceptors give rise to charge transfer complexes (CTC) which were characterized by UV-vis, FTIR, and EPR spectroscopy.
authors.affiliation: Institut de Ciència de Materials de Barcelona, CSIC, Campus Universitari, E-08193, Bellaterra, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: González
authors.forename: Nazario
authors.initials: N
authors.lastname: Martín
authors.forename: Luis
authors.initials: L
authors.lastname: Sánchez
authors.forename: José L.
authors.initials: JL
authors.lastname: Segura
authors.forename: Carlos
authors.initials: C
authors.lastname: Seoane
authors.forename: Isabel
authors.initials: I
authors.lastname: Fonseca
authors.forename: Félix H.
authors.initials: FH
authors.lastname: Cano
authors.forename: Josep
authors.initials: J
authors.lastname: Sedó
authors.forename: José
authors.initials: J
authors.lastname: Vidal-Gancedo
authors.forename: Concepció
authors.initials: C
authors.lastname: Rovira