Long‐range π‐type hydrogen bond in dimers CH2HF, CH2OH2O, and CH2ONH3

Abstract

AbstractUsing four basis bets, (6‐311G(d,p), 6‐31+G(d,p), 6‐31++G(2d,2p), and 6‐311++G(3df,3pd), the optimized structures with all real frequencies were obtained at the MP2 level for the dimers CH2OHF, 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 σ‐type hydrogen bonds. The bend of σ‐type H‐bond O…HY (YF, O, N) is illustrated and interpreted by an attractive interaction of a chemically intuitive π‐type hydrogen bond. The π‐type hydrogen bond is the interaction between one of the H atoms of CH2O and lone pair(s) on the F atom in HF, the O atom in H2O, or the N atom in NH3. In contrast with the above three dimers, for CH2OCH4, because there is not a π‐type hydrogen bond to bend its linear hydrogen bond, the structure of CH2OCH4 is noncyclic shaped. The interaction energy of hydrogen bonds and the π‐type H‐bond are calculated and discussed at the CCSD (T)/6‐311++G(3df,3pd) level. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005