Ab initio study on anomalous structures of anionic [(N-heterocycle)-CO2](-) complexes

作者：Oh Rena; Lim Eunhak; Zhang Xinxing; Heo Jiyoung; Bowen Kit H; Kim Seong Keun^*

来源：Journal of Chemical Physics, 2017, 146(13): 134304.

DOI：10.1063/1.4979576

Several unusual anionic complexes between carbon dioxide (CO2) and N-heterocycles (NHCs) possessing a significantly positive adiabatic electron affinity over 0.7eVwere studied by density functional theory calculations (UB3LYP/6-311++ g(d, p)). Unlike all previously reported [NHC-CO2](-) anions with a coplanar structure that ensures full delocalization of the negative charge through extended pi-conjugation, this new class of anionic [NHC-CO2] fi complexes has a strongly non-coplanar geometry and no pi-bond character between CO2 and NHC. Despite the fundamental differences in chemical bonding between all prior cases and the new class of [NHC-CO2](-) complexes, we found that the CO2 moiety in the latter still has a large negative charge (similar to 0.4 e) and a strongly bent geometry (O-C-O angle of similar to 140 degrees) just like in the former. This seemingly anomalous case was explained by a simple model based on the torsional steric effect and the electron affinities of the constituent moieties. Published by AIP Publishing.

• 出版日期2017-4-7