One-electron transfer processes in the reaction of elemental gallium, indium, and tin with tetrahalogeno-ortho-benzoquinones

Tin reacts with tetrahalogeno-o-benzoquinones X4C6O2 (X = Cl, Br) in refluxing toluene to give the tin(IV) catecholato species Sn(O2C6X4)2, and neutral and anionic derivatives have also been obtained. A mixture of Sn + X4C6O2-o + I2 + 1,10-phenanthroline (phen) yields SnI2(O2C6X4)phen. With gallium or indium (= M), the corresponding experiments give derivatives of MII (e.g., [M(O2C6X4)phen]2), or MIII (e.g., MI(O2C6X4)phen). Intermediate paramagnetic species were detected in the case of [Formula: see text], and a reaction mechanism involving one-electron transfer processes is proposed on the basis of these results. Solvated crystals of the compound InCl(O2C6Cl4)(C6H7N)3 were obtained from CH2Cl2 solution, and the structure of this molecule has been determined by X-ray crystallographic methods. Keywords: gallium, indium, tin, benzoquinones, oxidation.