Characteristic of structures and pi-hydrogen bond of dimers C2H4-nFn-HF (n=0,1,2)

Rui-Yan Li; Zhi-Ru Li; Di Wu; Ying Li; Wei Chen; Chia-Chung Sun

doi:10.1063/1.1799615

Characteristic of structures and pi-hydrogen bond of dimers C2H4-nFn-HF (n=0,1,2)

J Chem Phys. 2004 Nov 8;121(18):8775-81. doi: 10.1063/1.1799615.

Authors

Rui-Yan Li¹, Zhi-Ru Li, Di Wu, Ying Li, Wei Chen, Chia-Chung Sun

Affiliation

¹ State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.

PMID: 15527341
DOI: 10.1063/1.1799615

Abstract

By the counterpoise-correlated potential energy surface method (interaction energy optimization), five structures of the C(2)H(4-n)F(n)-HF (n = 0,1,2) dimers with all real frequencies have been obtained at MP2/aug-cc-pVDZ level. The influence of F substituent effect on the structure and pi-hydrogen bond of dimer has been discussed. For C(2)H(4-n)F(n)-HF (n = 1,2), the pi-hydrogen bonds are elongated comparing with that for C(2)H(4)-HF. For C(2)H(3)F-HF, g-C(2)H(2)F(2)-HF, cis-C(2)H(2)F(2)-HF, the pi-hydrogen bonds are further deformed. These changes (elongate, shift, and deformation) of pi-hydrogen bond mainly come from deformation of pi-electron cloud of C=C bond. The pi-electron cloud is pushed towards the one C atom, the pi H-bond shift also to the C direction. Since the two lobes of pi-electron cloud have deviated slightly from the molecular vertical plane passing through C=C bond, the pi-hydrogen bond is sloped. Intermolecular interaction energies of the dimers are calculated to be -3.9 for C(2)H(4)-HF, -2.8 for C(2)H(3)F-HF, -2.1 for g-C(2)H(2)F(2)-HF, -1.6 for cis-C(2)H(2)F(2)-HF, -1.3 kcal/mol for trans-C(2)H(2)F(2)-HF, at CCSD(T)/aug-cc-pVDZ level.