Carbon-13 chemical shifts of some pyridines, 2,2'-bipyridyls and 1,10-phenanthrolines

13C chemical shifts of pyridine, 2,2'-bipyridyl and 1,10-phenanthroline, and some of their methyl derivatives have been determined. All measurements were made on 0.25 M solutions in CDCl3, thus enabling comparisons of chemical shifts and substituent effects to be made without complications from solvent effects. For the three classes of compounds, common correlations exist between 13C chemical shifts and both CNDO/2 and INDO calculated carbon total electron densities, with the results suggesting that CNDO/2 calculations provide more suitable data for empirical correlations with 13C chemical shifts.