Gao Meng, Yang Xin, Cheng Jianbo, Li Qingzhong, Li Wenzuo, Loffredo Robert E
Laboratory of Theoretical and Computational Chemistry and School of Chemistry and Chemical Engineering, Yantai University, Yantai 264005(China).
Chemphyschem. 2013 Oct 7;14(14):3341-7. doi: 10.1002/cphc.201300558. Epub 2013 Jul 25.
The ternary systems of C(2)H(4) (C(2)H(2) or C(6)H(6))-MCN-HF (M=Cu, Ag, Au) and the respective binary systems were investigated to study the interplay between metal⋅⋅⋅π interactions and hydrogen bonds. The metal⋅⋅⋅π interactions in C(2)H(4)-MCN become stronger with the irregular order Ag<Cu<Au, while the hydrogen bonds in MCN-HF become weaker following the same order. The metal⋅⋅⋅π interactions are weakened as the H atoms in the π system are replaced with electron-withdrawing groups and enhanced by electron-donating groups. Type 1 of these ternary systems, in which MCN acts as Lewis base and acid simultaneously, is more stable than type 2, in which C(2)H(4) acts as a double Lewis base. Negative cooperativity is present in type 2 ternary systems with a weakening of the metal⋅⋅⋅π interactions and the hydrogen bonds. Positive cooperativity is found in type 1 ternary systems with an enhancement of the metal⋅⋅⋅π interactions and the hydrogen bonds, except for C(2)(CN)(4)-AuCN-HF-1. The weaker metal⋅⋅⋅π interaction in C(6)H(6)-AuCN has a greater enhancing effect on the hydrogen bond in AuCN-HF than those in C(2)H(4)-AuCN and C(2)H(2)-AuCN. These synergetic effects were analyzed with the natural bond orbital and energy decomposition.
研究了C₂H₄（C₂H₂或C₆H₆）-MCN-HF（M = Cu、Ag、Au）三元体系以及相应的二元体系，以研究金属⋅⋅⋅π相互作用与氢键之间的相互影响。C₂H₄-MCN中的金属⋅⋅⋅π相互作用按Ag<Cu<Au的不规则顺序增强，而MCN-HF中的氢键按相同顺序减弱。当π体系中的H原子被吸电子基团取代时，金属⋅⋅⋅π相互作用减弱，而被供电子基团增强。这些三元体系中的第1类，其中MCN同时作为路易斯碱和酸，比第2类更稳定，在第2类中C₂H₄作为双路易斯碱。在第2类三元体系中存在负协同效应，金属⋅⋅⋅π相互作用和氢键减弱。在第1类三元体系中发现正协同效应，金属⋅⋅⋅π相互作用和氢键增强，但C₂(CN)₄-AuCN-HF-1除外。C₆H₆-AuCN中较弱的金属⋅⋅⋅π相互作用对AuCN-HF中氢键的增强作用比对C₂H₄-AuCN和C₂H₂-AuCN中的增强作用更大。利用自然键轨道和能量分解分析了这些协同效应。
