Long-range pi-type hydrogen bond in the dimers CH2O-HF, CH2O-H2O, and CH2O-NH3

摘要

Using four basis sets, 6-311G(dp), 6-31+G(dp), 6-311++G(2d,2p), and 6311++G(3df,3pd), the optimized structures with all real frequencies were obtained at the MP2 level for dimers CH2O-ET, CH2O-H2O,CH2O-NH3, and CH2O-CH4. The structures of CH2O-Hf, CH2O-H2O, and CH2O-NH3 are cycle-shaped, which result from the larger bend of a-type hydrogen bonds. The bend of sigma-type H-bond O center dot center dot center dot H-Y (Y F, O, N) is illustrated and interpreted by an attractive interaction of a chemically intuitive pi-type hydrogen bond. The pi-type hydrogen bond is the interaction between one of the acidic H atoms of CH2O and lone pair(s) on the F atom in HF, the Od atom in H2O, or the N atom in NH3. By contrast with above the three dimers, for CH2O-CH4, because there is not a pi-type hydrogen-bond to bend its linear hydrogen bond, the structure of CH2O-CH, is a noncyctic shaped. The interaction energy of hydrogen bonds and the pi-type H-bond are calculated and discussed at the CCSD(T)/6-311 + +G(3df,3pd) level. (c) 2005 Wiley Periodicals, Inc.