ISSN:
0894-3230
Keywords:
Chemistry
;
Theoretical, Physical and Computational Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The known correlations between calorimetric and IR spectroscopic data on hydrogen bonding were reinvestigated for hydrogen bond donors (AH) dissolved in pure bases (B). Ninety-five AH···B systems were considered for which the enthalpies of specific interaction due to hydrogen bonding AH···B (ΔHAH/Bsp.int., kJ mol-1), the weight centers of A-H stretching bands (v, cm-1) and their integral absorption coefficients (α, 104 cm mmol-1) had been measured. The relationships between ΔHAH/Bsp.int. and the parameters of the infrared absorption spectra [weight center shifts Δv and the changes in the square roots of α (Δα1/2)] were analyzed. It was found that the dependence of ΔHAH/Bsp.int. on Δα1/2 consists of two nearly parallel straight lines: the first (-ΔHAH/Bsp.int. = 12·0 Δα1/2 + 0·4) corresponds to water and the weak C(SINGLE BOND)H and O(SINGLE BOND)H H-bond donors (chloroethylenes, acetylenes acetonitrile, nitromethane, chloroform, o, o′-di-tert-butylphenol); the second (-ΔHAH/Bsp.int. = 12·1 Δα1/2 -4·2) corresponds to the stronger N(SINGLE BOND)H and O(SINGLE BOND)H H-bond donors (N-methylaniline, pyrrole, alcohols, phenol, carbon acids). Non-linear dependences of ΔHAH/Bsp.int. on Δv were obtained for all C(SINGLE BOND)H, N(SINGLE BOND)H and O(SINGLE BOND)H H-bond donors except water [-ΔHAH/Bsp.int. = 59·9 Δv/(Δv + 674)]. Enthalpies of specific interaction for water obey another dependence [-ΔHH2O/Bsp.int./2 = 28·5 Δv/(Δv + 269)]. The ΔHAH/Bsp.int. values can be estimated by the above correlations with an accuracy of ±3 to ±6 kJ mol-1. These relationships obtained for solutions of H-bond donors in pure bases differ from the well known dependences determined for the AH···B hydrogen bonding in carbon tetrachloride medium.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
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