Twin hydrogen bonds with phosphine oxide: anticooperativity effects caused by competing proton donors.

In this computational work we study complexes with two equivalent intermolecular hydrogen bonds formed between trimethyl phosphine oxide and two identical proton donors ("twin" hydrogen bonds) for a set of 70 proton donor molecules. The changes in the phosphorus chemical shift and stretching frequency of the PO group upon complexation correlate quite well with the total strength of two hydrogen bonds. A set of explicit numerical dependences is proposed for assessing interatomic distances and hydrogen bond strengths from spectral data.

Complexes of phosphine oxides with substituted phenols: hydrogen bond characterization based on shifts of PO stretching bands.

In this work IR spectral characteristics of PO groups are used to evaluate the strength of OHO hydrogen bonds. Three phosphine oxides: triphenylphosphine oxide, tributylphosphine oxide and hexamethylphosphoramide are investigated as proton acceptors. The results of the experimental IR study and DFT calculation of 30 complexes formed by phosphine oxides with various substituted phenols or CFCHOH in CCl solution at room temperature are reported.

FTIR matrix isolation study of CDF3 in the region of CD stretching vibration: The spectroscopic manifestation of the Fermi resonance effects.

The IR spectra of CDF3 in the solid Ar and N2 matrices were measured and analyzed in the region of the Fermi polyads 2ν4/ν1/2ν2/ν4 + ν5, complicated by a close Fermi resonance ν4/ν3 + ν6. The symmetry lifting effect, observed in the N2 matrix, was found helpful for an accurate assignment of the individual components. The anharmonic calculation of the potential energy surface and the dipole moment function was performed on the MP2/aug-cc-pVTZ level.

IR Spectra of Hydrogen-Bonded Complexes of Trifluoroacetic Acid with Acetone and Diethyl Ether in the Gas Phase. Interaction between CH and OH Stretching Vibrations.

The spectra of complexes of trifluoroacetic acid (TFA) with acetone and diethyl ether (DEE) and their perdeuterated isotopologues were extracted from the spectra of the mixture of the compounds recorded at room temperature. The ν(OH) bands of the complexes with protiated and deuterated acetone notably differ from each other, whereas these ν(OH) bands are practically not affected by the deuteration of DEE. An assumption about the interaction of CH and OH groups in the (CH)-C═O···HO fragment is made.

The infrared study of fluoroform + methyl fluoride mixtures in argon and nitrogen matrices. Evidence of nonlinear blue-shifting complex formation.

The FTIR spectra of fluoroform + methyl fluoride mixtures trapped in argon and nitrogen matrices are studied at T~10-30 K. Spectroscopic changes observed in the region of the CH stretching mode of fluoroform are typical for weak blue shifting H - bonds of CH⋯F type. The degeneracy lifting effect found on E - type bands of fluoroform interacted with methyl fluoride suggests the complex formation of a nonlinear form.