SYNTHESIS AND CHARACTERIZATION OF DIHALOGENORUTHENIUM(IV)-TETRAPHENYLPORPHYRIN, DIPHENYLRUTHENIUM(IV)-TETRAPHENYLPORPHYRIN, AND PHENYLRUTHENIUM(III)-TETRAPHENYLPORPHYRIN COMPLEXES, INCLUDING THE CRYSTAL-STRUCTURE OF RU(TPP)BR2

The paramagnetic (S = 1) Ru(TPP)X2 complexes (X = halide) are made by treatment of [Ru(TPP)]2 with HBr, HCl, or I2 (TPP = the dianion of 5,10,15,20-tetraphenylporphyrin). The dibromo species (2) crystallizes in the tetragonal system, space group C4h5-I4/m, with a = 13.686 (9) angstrom, c = 9.711 (7) angstrom, and Z = 2. The structure has been refined on F2 to final R and R(w) values of 0.050 and 0.080, respectively, for 72 variables and 1639 observations; the value of R(F) for the 1354 reflections having F(o)2 greater-than-or-equal-to 3-sigma(F(o)2) is 0.034. The molecule has imposed symmetry 4/m. As a consequence, the porphyrin plane is strictly planar; the phenyl rings are perpendicular to this plane, as is the Ru-Br bond. The Ru-Br distance is 2.425 (2) angstrom, the shortest recorded for any Ru-Br bond. H-1 NMR isotropic shift data are consistent with pi-donation from the halide. With PhLi, 2 yields diamagnetic Ru(TPP)Ph2 (5), which can be thermally decomposed to Ru(TPP)Ph (6); kinetic data imply a stronger Ru-C bond in 5 compared to the corresponding octaethylporphyrin complex (by 2.6 kcal/mol). A light-induced O2 oxidation of 6 gives diamagnetic [Ru(TPP)Ph]2O.