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Cooperativity between OH···O and CH···O Hydrogen Bonds Involving Dimethyl Sulfoxide−H2O−H2O Complex

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journal contribution
posted on 11.10.2007, 00:00 by Qingzhong Li, Xiulin An, Baoan Gong, Jianbo Cheng
The cooperativity between the O−H···O and C−H···O hydrogen bonds has been studied by quantum chemical calculations at the MP2/6-311++G(d,p) level in gaseous phase and at the B3LYP/6-311++G(d,p) level in solution. The interaction energies of the O−H···O and C−H···O H-bonds are increased by 53 and 58%, respectively, demonstrating that there is a large cooperativity. Analysis of hydrogen-bonding lengths, OH bond lengths, and OH stretching frequencies also supports such a conclusion. By NBO analysis, it is found that orbital interaction plays a great role in enhancing their cooperativity. The strength increase of the C−H···O H-bond is larger than that of the O−H···O H-bond due to the cooperativity. The solvent has a weakening effect on the cooperativity.