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The Cooperativity of C–H···F Blue-Shifting Hydrogen Bonds. Static and Dynamic Calculations on CF3H Dimer, Trimer and Tetramer

Rodziewicz P., Rutkowski K. S., Melikova S. M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

1075-1084

EN

Static and dynamic density functional theory calculations on CF3H dimer, trimer and tetramer are presented. All the structures analyzed present the cyclic C–H···F pattern. The energetic, geometrical and vibrational contributions resulting from cooperative effects have been analyzed. The Car-Parrinello molecular dynamics technique has been used to estimate the cooperative effects temperature dependence. The results of simulations might support future molecular beam or supersonic jet experimental studies.

2

Blue and Red Frequency Shift Effects Related with XA–H...B-Y Complex Formation

Rutkowski K. S., Karpfen A., Melikova S. M., Rodziewicz P.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

965-980

EN

Results of FTIR spectroscopic measurements in cryosolutions and ab initio calculations performed for a set of complexes stabilized by conventional and “im proper” H-bonds have been presented and analyzed. The main attention is paid to the blue and red frequency shift effects on the stretching vibrations which were ob served/or predicted for complexes of a weak to medium strength, formed between so called CH acids and various electron donor counter parts. It has been shown that the features of the dipole moment function and the type of intramolecular coupling between the vicinal bonds of the inter acting counter parts predefine in the most extent the sign of the frequency shift of respective stretching vibrations.

3

FT-IR Studies of CH...B Interactions in Fluoroform Containing Cryosolutions

Melikova S., Rutkowski K. S., Rodziewicz P., Koll A.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 9

1271-1285

EN

A transition from a blue shifted frequency of the _(CH) vibrations of CF3H to a conventional red frequency shift, accompanied by unusually varying integrated intensity of the corresponding _1 band, have been studied in CF3H/B systems, where B = Ar, N2, CO, CO2, O(CD3)2, NH3, and N(CD3)3. DFT/B3LYP and ab initio MP2 calculations, utilizing the 6-311++G(3df,3pd) basis set, predict a weakly H-bond-like linear F3CH…B complex formation in the series studied and reproduce experimentally observed variations of spectroscopic parameters. The results obtained are treated in the framework of induced dipole moment, taking into account opposite directions of the CH bond dipole moment and the dipole moment of the whole molecule. In the range of overtone and combination bands of fluoroform, new weak bands have been detected. They were attributed to simultaneous excitations of vibrations of interacting CF3HandB(=CO,CO2) molecular pairs.