Hydrogen Transfer In The Transfer Hydrogenation Of Acetophenone Catalyzed By Ruthenium-acetamido Complex. A Theoretical Mechanistic Investigation

In this paper, the mechanism of transfer hydrogenation of acetophenonecatalyzed by Ruthenium-Acetamido complex was studied using densityfunction theory (DFT) method. The catalytic cycle of transfer hydrogenationconsists of hydrogen transfer (HT) step和dehydrogenation (DH) step ofiso-propanol (IPA). Inner sphere mechanism (Path1and Path7) and outersphere mechanism (Path2-6) in HT step are fully investigated. Calculatedresults indicate that DH step of IPA (from~i1to~i2) is the rate-determining stepin the whole catalytic cycle, which has a potential energy barrier of16.2kcal/mol. On the other hand, the maximum potential energy barriers of Path1-7In HT step are5.9,12.7,24.4,16.8,23.7,7.2和6.1kcal/mol,respectively. The inner sphere pathways (Path1and Path7) are favorablehydrogen transfer modes compared with outer sphere pathways, and theproton transferred to the oxygen atom of acetophenone comes from hydroxyl group but not from amino group of acetamido ligand. Those theoretical resultsare in agreement with experimental report. However, in view of this DFTstudy in inner sphere mechanism of HT step, hydride transfer and protontransfer are concerted and asynchronous hydrogen transfer but not stepwiseone,和hydride transfer precedes proton transfer in this case.