title: Outer-Sphere 2 e-/2 H+Transfer Reactions of Ruthenium(II)-Amine and Ruthenium(IV)-Amido Complexes.
abstract: A diverse set of 2 e-/2 H+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 reactions occur without substrate binding to the ruthenium center, but instead with precursor complex formation by hydrogen bonding. The free energies of the reactions vary over more than 90 kcal mol-1, but the rates are more dependent on the type of X-H bond involved than the associated ΔG°. There is a kinetic preference for substrates that have the transferring hydrogen atoms 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 2 e-/2 H+transfers.
authors.affiliation: Department of Chemistry, University of Washington, USA.|INQUINOA-CONICET, Universidad Nacional de Tucumán, Ayacucho 471 (T4000INI), San Miguel de Tucumán, Argentina.
authors.forename: Mauricio
authors.identifier: 0000-0002-5598-0814
authors.initials: M
authors.lastname: Cattaneo
authors.affiliation: Department of Chemistry, University of Washington, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Ryken
authors.affiliation: Department of Chemistry, University of Washington, USA.|Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT, 06520, USA.
authors.forename: James M
authors.identifier: 0000-0002-3943-5250
authors.initials: JM
authors.lastname: Mayer
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D000577:Amides / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D053138:Cyclohexenes / Q000737:chemistry; D004579:Electron Transport; D004583:Electrons; D006834:Hydrazines / Q000737:chemistry; D006860:Hydrogen Bonding; D011522:Protons; D011809:Quinones / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000577:Amides; D000588:Amines; D056831:Coordination Complexes; D053138:Cyclohexenes; D006834:Hydrazines; D011522:Protons; D011809:Quinones; D013438:Sulfhydryl Compounds; C048401:1,4-cyclohexadiene; D015082:2,2'-Dipyridyl; D012428:Ruthenium
keywords: amido functional groups; multielectron transfers; multiproton transfers; proton-coupled electron transfer (PCET); ruthenium complexes