Rio, CarolinaRibeiro da Silva, M. A. V.Morais, V. M. F.Matos, M. A. R.2014-10-202014-10-2019950022-3263http://hdl.handle.net/10400.1/5379The following standard molar enthalpies of formation in the gaseous state at 298.15 K were determined from the enthalpies of combustion of the crystalline solids and the respective enthalpies of sublimation: 2,2’-bipyridine, 267.9 f 3.0 kJ mol-’; 2,4’-bipyridine, 284.2 f 2.7 kJ mol-’; 4,4‘- bipyridine, 293.1 f 3.6 kJ mol-’. Ab initio geometry optimizations of these molecules at the 3-21G level suggest that those with at least one ortho nitrogen atom assume near planar conformations preferentially, while the others have nonplanar most stable forms.engjournal articlehttp://dx.doi.org/10.1021/jo00121a056AUT: CRI01087;