The 1H NMR titration method is used to investigate through‐space and through‐bond effects on the association of diols with pyridine in benzene. Alkan‐1,n‐diols (n goes from 2 to 10), DL and meso isomers of butan‐2,3‐, pentan‐2,4‐ and hexan‐2,5‐diols, two adamantane diols and a bicyclo[2.2.2]octane diol are compared with alkanols. The –CH2OH groups of the tri‐ and bicyclic compounds behave as if they were independent, with limiting OH proton shifts (at very low concentration) and both the first and the second association constants similar to those of a primary alcohol. In contrast, the alkane diols, with n = 2–4, display unusually high limiting shifts, ranging from 1.0 to 1.5 ppm (2.1 ppm for one methyl‐substituted diol). For these diols the first dissociation constant and the sum of the OH proton shifts in the 1:1 pyridine: diol complex are enhanced. This may be attributed to small cooperative effects, implying intramolecular hydrogen bonding, for n = 3 and 4, but for n = 2 a through‐bond effect accounts for most of the increase. Substituent interaction falls off sharply for n = 5 and is practically negligible for n = 10, for which the second association constant is close to the first. A sterically hindered BiEDOT diol, 2,2′‐bis{(3,4‐ethylenedioxythienyl)‐5‐[3‐(2,2,4,4‐tetramethylpentan‐3‐ol)]} behaves like the polycyclic compounds, with the two C(t‐Bu)2OH groups independent. Copyright © 2010 John Wiley & Sons, Ltd.

The proton NMR spectra of several 1,2-diols in benzene have been analysed so as to associate each magnetically nonequivalent proton with its chemical shift. The shifts and coupling constants of the OH and methylene protons of ethane-1,2-diol have been determined in a wide range of solvents. The conformer distribution and the proton NMR shifts of these 1,2-diols in benzene have been computed on the basis of density functional theory. The solvent is included using the integral-equation-formalism polarizable continuum model implemented in Gaussian 09. Relative Gibbs energies for all stable conformers are calculated at the Perdew, Burke and Enzerhof (PBE)0/6-311 + G(d,p) level, and shifts are calculated using the gauge-including atomic orbital method with the PBE0/6-311 + G(d,p) geometry but using the cc-pVTZ basis set. Previous calculations on ethane-1,2-diol and propane-1,2-diol have been corrected and extended. New calculations on tert-butylethane-1,2-diol, phenylethane-1,2-diol, butane-2,3-diols (dl and meso) and cyclohexane-1,2-diols (cis and trans) are presented. Overall, the computed NMR shifts are in good agreement with experimental values for the OH protons but remain systematically high for CH protons. Some results based on the Gaussian 03 solvation model are included for comparison.