Matus Myrna H, Arduengo Anthony J, Dixon David A
Chemistry Department, The University of Alabama, Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336, USA.
J Phys Chem A. 2006 Aug 24;110(33):10116-21. doi: 10.1021/jp061854u.
The heats of formation of N(2)H, diazene (cis- and trans-N(2)H(2)), N(2)H(3), and hydrazine (N(2)H(4)), as well as their protonated species (diazenium, N(2)H(3)(+), and hydrazinium, N(2)H(5)(+)), have been calculated by using high level electronic structure theory. Energies were calculated by using coupled cluster theory with a perturbative treatment of the triple excitations (CCSD(T)) and employing augmented correlation consistent basis sets (aug-cc-pVnZ) up to quintuple-zeta, to perform a complete basis set extrapolation for the energy. Geometries were optimized at the CCSD(T) level with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. Core-valence and scalar relativistic corrections were included, as well as scaled zero point energies. We find the following heats of formation (kcal/mol) at 0 (298) K: DeltaH(f)(N(2)H) = 60.8 (60.1); DeltaH(f)(cis-N(2)H(2)) = 54.9 (53.2); DeltaH(f)(trans-N(2)H(2)) = 49.9 (48.1) versus >/=48.8 +/- 0.5 (exptl, 0 K); DeltaH(f)(N(2)H(4)) = 26.6 (23.1) versus 22.8 +/- 0.2 (exptl, 298 K); DeltaH(f)(N(2)H(3)) = 56.2 (53.6); DeltaH(f)(N(2)H(3)(+)) = 231.6 (228.9); and DeltaH(f)(N(2)H(5)(+)) = 187.1 (182.7). In addition, we calculated the heats of formation of CH(3)NH(2), CH(3)NNH, and CH(3)HNNHCH(3) by using isodesmic reactions and at the G3(MP2) level. The calculated results for the hydrogenation reaction RNNR + H(2) --> RHNNHR show that substitution of an organic substituent for H improved the energetics, suggesting that these types of compounds may be possible to use in a chemical hydrogen storage system.
利用高水平电子结构理论计算了N(2)H、重氮烯（顺式和反式-N(2)H(2)）、N(2)H(3)和肼（N(2)H(4)）及其质子化物种（重氮鎓、N(2)H(3)(+)和肼鎓、N(2)H(5)(+)）的生成热。通过使用耦合簇理论并对三重激发进行微扰处理（CCSD(T)），并采用高达五重zeta的增强相关一致基组（aug-cc-pVnZ）来计算能量，以对能量进行完整基组外推。在CCSD(T)水平上使用aug-cc-pVDZ和aug-cc-pVTZ基组对几何结构进行了优化。包括了芯价和标量相对论校正以及缩放后的零点能。我们在0（298）K时得到以下生成热（kcal/mol）：ΔH(f)(N(2)H)=60.8（60.1）；ΔH(f)(顺式-N(2)H(2))=54.9（53.2）；ΔH(f)(反式-N(2)H(2))=49.9（48.1），而实验值（0 K）≥48.8±0.5；ΔH(f)(N(2)H(4))=26.6（23.1），而实验值（298 K）为22.8±0.2；ΔH(f)(N(2)H(3))=56.2（53.6）；ΔH(f)(N(2)H(3)(+))=231.6（228.9）；以及ΔH(f)(N(2)H(5)(+))=187.1（182.7）。此外，我们通过等键反应并在G3(MP2)水平上计算了CH(3)NH(2)、CH(3)NNH和CH(3)HNNHCH(3)的生成热。氢化反应RNNR + H(2) --> RHNNHR的计算结果表明，用有机取代基取代H改善了能量学性质，这表明这类化合物可能可用于化学储氢系统。
