Thermochemical studies of two N-(diethylaminothiocarbonyl)benzimido derivatives

Abstract

The standard ( p ∘ = 0.1 MPa) molar energies of combustion in oxygen of N-(diethylaminothiocarbonyl)- N′-monoethylbenzamidine, PhCNHEtNCSNEt 2 (DATMB), and N-(diethylaminothiocarbonyl)benzimido ethylester, PhCOEtNCSNEt 2 (DATBE), were measured, at T = 298.15 K, by rotating-bomb calorimetry. The standard molar enthalpies of sublimation of these compounds were determined using Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the title compounds, in their crystalline and gaseous phases, respectively. Compounds - Δ c U m ∘ ( cr ) / ( kJ · mol - 1 ) - Δ f H m ∘ ( cr ) / ( kJ · mol - 1 ) Δ cr g H m ∘ / ( kJ · mol - 1 ) N-(Diethylaminothiocarbonyl)- N′-monoethylbenzamidine (DATMB) 9053.6 ± 3.9 45.7 ± 4.4 141.2 ± 1.2 N-(Diethylaminothiocarbonyl)benzimido ethylester (DATBE) 8780.9 ± 4.0 176.2 ± 4.4 135.6 ± 2.6 The standard molar enthalpies of formation for the two title compounds, in the gaseous state, were also calculated based on density functional theory at the B3LYP/6-311++G(2df,p)//6-31+G(d,p)-level of theory, anchored on previous experimental data for the standard molar enthalpy of formation of N-(diethylaminothiocarbonyl)-benzamidine.