Invited for the cover of this issue is the group of Xinzhen Yang at Institute of Chemistry, Chinese Academy of Sciences. The image depicts a series of computationally designed iron, cobalt, and manganese cyclopentadienone catalysts for hydrogenation of carbon dioxide to methanol. Read the full text of the article at 10.1002/chem.201701200.
Density functional theory computations reveal mechanistic insights into Cu and chiral phosphoric acid (CPA) catalyzed enantioconvergent amination of racemic benzenesulfonohydrazide. The OÀ O bond homolysis of tert-butyl 4phenylbutaneperoxoate was found to be the turnover-limiting step with a total free energy barrier of 19.1 kcal/mol. The enantioconvergent amination is realized to obtain the same intermediate through prochiral carbon atom. The order and mode of hydrogen atom transferred by CPA and tert-butyloxy have a significant influence on the enantioselectivity and energy barriers. The olefinic side product generated by βhydride elimination is 9.9 kcal/mol thermodynamically less favourable. A series of phosphoric acids are predicted as promising co-catalysts with lower barriers for OÀ O bond homolysis.
Computational Chemistry Mechanistic insights of the hydrogenation of ethyl acetate to ethanol catalyzed by SNS pincer ruthenium complexes are revealed by density functional theory calculations. Two cascade catalytic cycles with the same catalyst for the production of two ethanol molecules are shown along the frame of the glasses in the picture. As reported by X. Yang et al. in their Full Paper on page 1950 ff., the new mechanism features a five‐coordinated catalyst with trans sulfur atoms, an ethanol‐assisted proton transfer for dihydrogen cleavage, a direct hydride transfer from Ru to the carbonyl carbon, and an out‐sphere C–OEt bond cleavage for the formation of the aldehyde.
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