Outer-sphere 2e−/2H+ transfer reactions of RuII(amine)/RuIV(amido) complexes

MAURICIO CATTANEO; SCOTT A. RYKEN; JAMES M. MAYER

Angewandte Chemie

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2017 vol. 56 p. 3675 - 3678

1433-7851

A diverse set of 2e?/2H+ reactions are described that interconvert [RuII(bpy)(en*)2]2+ and [RuIV(bpy)(en-H*)2]2+ (bpy = 2,2?-bipyridine, en* = H2NCMe2CMe2NH2, en*-H = H2NCMe2CMe2NH?), forming or cleaving different O-H, N-H, S-H and C-H bonds. The reactions involve quinones, hydrazines, thiols and 1,3-cyclohexadiene. These proton-coupled electron transfer (PCET) reactions occur without substrate binding to the ruthenium center, but with precursor complex formation by hydrogen bonding. The free energies of the reactions vary over more than 90 kcal mol-1, but the rates vary more with the kind of X?H bond involved than with this ΔG°. There is a kinetic preference for substrates that have the transferring H?s in close proximity, such as ortho-tetrachlorobenzoquinone over its para isomer and 1,3-cyclohexadiene over its 1,4-isomer, perhaps hinting at the potential for concerted 2e−/2H+ transfers.