Thermochemistry of 2,2′-dipyridil N-oxide and 2,2′-dipyridil N, N′-dioxide. The dissociation enthalpies of the N−O bonds

Abstract

In this paper, the first, second and mean (N−O) bond dissociation enthalpies (BDEs) were derived from the standard ( p° = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, Δ f H m ∘ ( g ) , at T = 298.15 K, of 2,2′-dipyridil N-oxide and 2,2′-dipyridil N, N′-dioxide. These values were calculated from experimental thermodynamic parameters, namely from the standard ( p° = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, Δ f H m ∘ ( cr ) , at T = 298.15 K, obtained from the standard molar enthalpies of combustion, Δ c H m ∘ , measured by static bomb combustion calorimetry, and from the standard molar enthalpies of sublimation, at T = 298.15 K, determined from Knudsen mass-loss effusion method.