Structural Determination of Ruthenium−Porphyrin Complexes Relevant to Catalytic Epoxidation of Olefins

A reproducible synthesis of a competent epoxidation catalyst, [RuVI(TPP)(O)2] (TPP = tetraphenylporphyrin dianion),
starting from [RuII(TPP)(CO)L] (L = none or CH3OH), is described. The molecular structure of the complex was
determined by using ab initio X-ray powder diffraction (XRPD) methods, and its solution behavior was in detail
investigated by NMR techniques such as PGSE (pulsed field gradient spin-echo) measurements. [RuIV(TPP)(OH)]2O, a reported byproduct in the synthesis of [RuVI(TPP)(O)2], was synthesized in a pure form by oxidation of
[RuII(TPP)(CO)L] or by a coproportionation reaction of [RuVI(TPP)(O)2] and [RuII(TPP)(CO)L], and its molecular
structure was then determined by XRPD analysis. [RuVI(TPP)(O)2] can be reduced by dimethyl sulfoxide or by
carbon monoxide to yield [RuII(TPP)(S-DMSO)2] or [RuII(TPP)(CO)(H2O)], respectively. These two species were
characterized by conventional single-crystal X-ray diffraction analysis.