The nature of “A,B,C”-type infrared spectra of strongly hydrogen-bonded systems; pseudo-maxima in vibrational spectra

1969 ◽  
Vol 0 (23) ◽  
pp. 1431-1433 ◽  
Author(s):  
M. F. Claydon ◽  
N. Sheppard
Keyword(s):  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Infrared spectra of hydrogen bonded adducts of 2,6-dichlorophenols and oxygen bases

1985 ◽  
Vol 63 (12) ◽  
pp. 3568-3572 ◽  
Author(s):  
R. Wolny ◽  
A. Koll ◽  
L. Sobczyk
Keyword(s):  
Infrared Spectra ◽  
Infrared Region ◽  
Hydroxyl Group ◽  
Vibration Band ◽  
Inversion Point ◽  
Integrated Intensity ◽  
Stretching Vibration ◽  
Background Absorption ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Infrared spectra of hydrogen bonded complexes of 2,6-dichlorophenol derivatives and oxygen bases have been studied over a broad ΔpKa range (from −10.55 to +1.69). For the complexes of 1:1 stoichiometry typical evolution of spectra, similar to those for other hydrogen bonded systems, have been found. With an increase of ΔpKa the hydroxyl group stretching vibration band shifts to lower frequencies until the inversion region is reached, where hydrogen bonded (HB) and proton transfer (PT) forms occur in equilibrium, then abroad background absorption is observed. The centre of gravity of the broad protonic bands, veg, calculated from the integrated intensity over the whole infrared region have been correlated with ΔpKa and the contribution of the PT form. It has been shown that the minimum on the plot veg vs. ΔpKa is reached close to the inversion point, where KPT = 1. The observed correlations and the change in the shape of the broad protonic absorption are consistent with expectations of theories based on the concept of the double minimum potential function and the stochastic mechanisms of band broadening.

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