A theoretical investigation on the conformation and the interaction of CHF2OCF2CHF2 (desflurane II) with one water molecule

作者：Sutradhar Dipankar; Zeegers Huyskens Therese; Chandra Asit K^*

来源：Journal of Molecular Modeling, 2013, 19(11): 5045-5052.

DOI：10.1007/s00894-013-2016-4

• CHF2OCF2CHF2
• Frequency shift
• Hydrogen bonding
• M062X
• MP2
• NBO analysis
• Water

The conformation and the interaction of CHF2OCF2CHF2 (desflurane II) with one water molecule is investigated theoretically using the ab initio MP2/aug-cc-pvdz and DFT-based M062X/6-311++G(d,p) methods. The calculations include the optimized geometries, the harmonic frequencies of relevant vibrational modes along with a natural bond orbital (NBO) analysis including the NBO charges, the hybridization of the C atom and the intra- and intermolecular hyperconjugation energies. In the two most stable conformers, the CH bond of the F2HCO- group occupies the gauche position. The hyperconjugation energies are about the same for both conformers and the conformational preference depends on the interaction between the non-bonded F and H atoms. The deprotonation enthalpies of the CH bonds are about the same for both conformers, the proton affinity of the less stable conformer being 3 kcal mol(-1) higher. Both conformers of desflurane II interact with water forming cyclic complexes characterized by CHaEuro broken vertical bar O and OHaEuro broken vertical bar F hydrogen bonds. The binding energies are moderate, ranging from -2.4 to -3.2 kcal mol(-1) at the MP2 level. The origin of the blue shifts of the nu(CH) vibrations is analyzed. In three of the complexes, the water molecule acts as an electron donor. Interestingly, in these cases a charge transfer is also directed to the non bonded OH group of the water molecule. This effect seems to be a property of polyfluorinated ethers.

• 出版日期2013-11