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

Tin reacts with tetrahalogeno-o-benzoquinones X 4 C 6 O 2 (X = Cl, Br) in refluxing toluene to give the tin(IV) catecholato species Sn(O 2 C 6 X 4 ) 2 , and neutral and anionic derivatives have also been obtained. A mixture of Sn + X 4 C 6 O 2 -o + I 2 + 1,10-phenanthroline (phen) yields SnI 2 (O 2 C 6 X 4 )phen. With gallium or indium (= M), the corresponding experiments give derivatives of M II (e.g., [M(O 2 C 6 X 4 )phen] 2 ), or M III (e.g., MI(O 2 C 6 X 4 )phen). Intermediate paramagnetic species were detected in the case of , and a reaction mechanism involving one-electron transfer processes is proposed on the basis of these results. Solvated crystals of the compound InCl(O 2 C 6 Cl 4 )(C 6 H 7 N) 3 were obtained from CH 2 Cl 2 solution, and the structure of this molecule has been determined by X-ray crystallographic methods. Keywords: gallium, indium, tin, benzoquinones, oxidation.