Mauricio Cattaneo1,2, Scott A Ryken1, James M Mayer1,3. 1. Department of Chemistry, University of Washington, USA. 2. INQUINOA-CONICET, Universidad Nacional de Tucumán, Ayacucho 471 (T4000INI), San Miguel de Tucumán, Argentina. 3. Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT, 06520, USA.
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*=H2 NCMe2 CMe2 NH2 , en*-H=H2 NCMe2 CMe2 NH- ), 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.
A diverse set of 2 e- /2 H+ reactions are described that interconvert [RuII (n class="Chemical">bpy)(en*)2 ]2+ and [RuIV (bpy)(en-H*)2 ]2+ (bpy=2,2'-bipyridine, en*=H2NCMe2 CMe2 NH2 , en*-H=H2NCMe2 CMe2 NH- ), 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: Kamaluddin Abdur-Rashid; Sean E Clapham; Alen Hadzovic; Jeremy N Harvey; Alan J Lough; Robert H Morris Journal: J Am Chem Soc Date: 2002-12-18 Impact factor: 15.419
Authors: Mauricio Cattaneo; Giovanny A Parada; Adam L Tenderholt; Werner Kaminsky; James M Mayer Journal: Eur J Inorg Chem Date: 2021-09-12 Impact factor: 2.551