[2+3] Cycloaddition of Ethylene to Transition Metal Oxo Compounds. Analysis of Density Functional Results by Marcus Theory

Abstract

Density functional results on the [2+3] cycloaddition of ethylene to various transition metal complexes MO(3)(q) and LMO(3)(q) (q = -1, 0, 1) with M = Mo, W, Mn, Tc, Re, and Os and various ligands L = Cp, CH(3), Cl, and O show that the corresponding activation barriers DeltaE(double dagger) depend in quadratic fashion on the reaction energies DeltaE(0) as predicted by Marcus theory. A thermoneutral reaction is characterized by the intrinsic reaction barrier DeltaE(0) of 25.1 kcal/mol. Both ethylene [2+3] cycloaddition to an oxo complex and the corresponding homolytic M-O bond dissociation are controlled by the reducibility of the transition metal center. Indeed, from the easily calculated M-O bond dissociation energy of the oxo complex one can predict the reaction energy DeltaE(0) and hence, by Marcus theory, the corresponding activation barrier DeltaE. This allows a systematic representation of more than 25 barriers of [2+3] cycloaddition reactions that range from 5 to 70 kcal/mol.

Cascade cyclization of 1-(2-yl-3-phenylprop-2-enyl)-6-oxo-1,6-dihydropyridine-2-carbonitrile radical: Mechanistic insights from DFT study

“…In order to evaluate thermodynamical and kinetic effects of activation processes, we used the Marcus theory [80][81][82][83][84][85] to separate their contributions to reaction barrier. The method was originally developed for describing charge transfer problems, and now it has been widely applied to various organic reactions [86][87][88][89][90][91][92][93]. In a reaction, the activation barrier (DE -) is composed of intrinsic barrier ðDE -0 Þ and thermodynamic contribution ðDE -therm Þ and can be described as…”

Kinetic detection of osmium(VI) ester intermediates during the OsO4‐mediated aqueous dihydroxylation of chloroethylenes

“…At first sight, this might seem to contradict well established quantum chemical calculations, which showed that the osmate ester formation is highly exergonic. The calculated energy changes for ethylene as an oxidizable alkene were −21.2 kcal mol −1 (=−88.7 kJ mol −1 ) and −18.1 kcal mol −1 (=−75.7 kJ mol −1 ) . Without the intention to question the accuracy of these results, the next paragraphs will show that the results of these quantum chemical calculations are irrelevant for the present study.…”

“…The calculated energy changes for ethylene as an oxidizable alkene were −21.2 kcal mol −1 (=−88.7 kJ mol −1 ) [46] and −18.1 kcal mol −1 (=−75.7 kJ mol −1 ). [47] Without the intention to question the accuracy of these results, the next paragraphs will show that the results of these quantum chemical calculations are irrelevant for the present study.…”

Theoretical study on SH2 reaction of methyl radical with three‐membered ring

“…Marcus theory was originally developed for electron‐transfer reactions . Subsequently, it has been successfully applied to a wide variety of organic reactions, such as cyclization …”