The oxo-vanadium-catalyzed redox disproportionation of activated alcohols (oxidation–reductive coupling, Ox–RC) produces carbonyl compounds and hydrocarbon dimers. A mechanistic study of this novel reaction is reported herein. Following our initial disclosure, new findings include the following: (1) The [(salimin)­VO2]−-catalyzed Ox–RC of Ph2CHOH in the presence of fluorene affords the products of H-atom abstraction and all possible hydrocarbon dimers. (2) Electronic substituent effects on the relative rates of Ox–RC with respect to 4-X-BnOH reactants and Bu4N­[(Y-salimin)­VO2] catalysts (1a–c) reveal (a) a correlation of the oxidation rate of X-BnOH reactants with the radical σ parameter and (b) correlation of the oxidation rate for (Y-salimin)­VO2 – with the standard Hammett σ parameter. (3) The ease of electrochemical reduction of 1a–c is Y = NO2 > OMe > H. (4) Ambient 1H NMR studies of the interaction of 1 with alcohols suggest only a weak equilibrium association. (5) Density functional theory computational modeling of the Ox–RC reaction supports a ping-pong-type catalytic pathway, beginning with alcohol oxidation by (salimin)­VO2 –, preferably by stepwise-H-atom transfer from the alcohol to 1, affording the carbonyl product and the reduced (salimin)­V­(III)­(OH)2 –. The reduction half-reaction likely begins with condensation of the latter species with R2CHOH to give the alkoxide complex (salimin)­V­(OR)­OH–; homolysis of the R···OV­(III)­(salimin) bond affords (salimin)­V­(IV)­OH­(O)− and the R-radical; the latter dimerizes and the former can disproportionate via H-transfer to reform catalyst (salimin)­VO2 – (1) and (salimin)­V­(OH)2 –.

A series of ruthenium(V)À oxo compounds, LRu(V)O (n) [L = bipyridinedicarboxylate (BDA), alpha-hydroxycarboxylate (AHA), porphyrin (POR), dimethylglyoximate (DMG), and nitrilotriacetate (NTA); n = + 1,0, À 1] are evaluated by Density Functional Theory for their ability to produce dioxygen through coupling of Ru(V)À oxo species, bimetallic peroxides (LRu(IV)-OÀ OÀ Ru(IV) L), and dioxygen (LRu(IV)-O 2 ) complexes. Anionic RuÀ oxo complexes (AHA) 2 RuO À (2) and ( NTA)Ru(O)Cl À (5 e) have prohibitively large free energies of coupling, while neutral and monocationic species (1 b, 3-5 a-d) show small to moderate free energies of coupling. Transition states for OÀ O coupling were found for (NTA)RuO (5 a), (NTA)RuO(NH 3 ) (5 c), (NTA)RuO (Pyr) (5 d), (DMG) 2 ClRu(O) ( 8) and (POR)RuO(Cl) ( 9), yielding moderate activation energies in the range of 18-22 kcal/mol. The overall oxygen evolution reaction (OER) free energies decrease in favourability as the coordination number of LRuO decreases, i. e. 7 > 6 > 5. The modest activation energies and free energies along the reaction coordinate for (NTA)(L)RuO and (POR)ClRu(O) suggest that these species would undergo kinetically and thermodynamically favorable oxygen evolution.