TY - DATA T1 - Toward a Low-Barrier Transition-Metal-Free Catalysis of Hydrogenation Reactions:  A Theoretical Mechanistic Study of HAlX4-Catalyzed Hydrogenations of Ethene (X = F, Cl, and Br) PY - 2000/07/18 AU - Stefan Senger AU - Leo Radom UR - https://acs.figshare.com/articles/journal_contribution/Toward_a_Low-Barrier_Transition-Metal-Free_Catalysis_of_Hydrogenation_Reactions_A_Theoretical_Mechanistic_Study_of_HAlX_sub_4_sub_-Catalyzed_Hydrogenations_of_Ethene_X_F_Cl_and_Br_/3721314 DO - 10.1021/jp001226r.s001 L4 - https://ndownloader.figshare.com/files/5813016 KW - 100 kJ mol KW - HX KW - Hydrogenation KW - 367 kJ mol KW - Catalysi KW - Theoretical Mechanistic Study KW - hydrogenation KW - Br KW - pathway KW - CH KW - barrier KW - HAlX 4 KW - Cl KW - ethene KW - MP KW - HAlX 4 species N2 - Ab initio molecular orbital theory at the MP2/6-311+G(3df,2p)//B3-LYP/6-31G(d) level has been used to study the transition-metal-free catalysis of the hydrogenation of ethene. Catalysis by HX, (HX)2 and HAlX4 (X = F, Cl, and Br) has been examined. Both concerted pathways and stepwise pathways involving CH3CH2X-type intermediates have been characterized. The former are energetically preferred in the case of the HX- and (HX)2-catalyzed reactions. However, for the HAlX4-catalyzed hydrogenations, concerted and stepwise mechanisms are found to have similar barriers. The HAlX4 species are found to be very effective hydrogenation catalysts, reducing the barrier for the hydrogenation of ethene from the value of 367 kJ mol-1 in the uncatalyzed process to less than 100 kJ mol-1 for all the halogens (X). ER -