Computational Study on N–N Homolytic Bond Dissociation Enthalpies of Hydrazine Derivatives

Abstract

The hydrazine derivatives have been regarded as the important building blocks in organic chemistry for the synthesis of organic N-containing compounds. It is important to understand the structure-activity relationship of the thermodynamics of N-N bonds, in particular, their strength as measured by using the homolytic bond dissociation enthalpies (BDEs). We calculated the N-N BDEs of 13 organonitrogen compounds by eight composite high-level ab initio methods including G3, G3B3, G4, G4MP2, CBS-QB3, ROCBS-QB3, CBS-Q, and CBS-APNO. Then 25 density functional theory (DFT) methods were selected for calculating the N-N BDEs of 58 organonitrogen compounds. The M05-2X method can provide the most accurate results with the smallest root-mean-square error (RMSE) of 8.9 kJ/mol. Subsequently, the N-N BDE predictions of different hydrazine derivatives including cycloalkylhydrazines, N-heterocyclic hydrazines, arylhydrazines, and hydrazides as well as the substituent effects were investigated in detail by using the M05-2X method. In addition, the analysis including the natural bond orbital (NBO) as well as the energies of frontier orbitals were performed in order to further understand the essence of the N-N BDE change patterns.

Improving the Stability of Trinitramide by Chemical Substitution: N(NF2)3 has Higher Stability and Excellent Propulsion Performance

“…Another example is FOX‐7 [(H 2 N) 2 C=C(NO 2 ) 2 ] [20], whose high stability and insensitivity at least partly can be attributed to the resonance interaction between the amino and nitro groups. A similar but much stronger effect is observed in H 2 N−NO 2 , which has a N−N BDE of 267 kJ/mol compared to 50 kJ/mol in O 2 N−NO 2 [21]. Rather surprisingly, we found a very low N‐NO 2 BDE of 54 kJ/mol in N(NO 2 ) 2 NH 2 .…”

A general and selective Ni-catalysed reductive amination using hydrazine hydrate as facile hydrogen and nitrogen sources

“…According to these mechanistic study results and literature reports, 12–16 we propose a tentative mechanism for this N 2 H 4 -mediated reductive amination (Fig. 5).…”

“…Then, subsequent reduction of 8 occurs, resulting in the final product primary amine 3 by reductive cleavage of the N–N bond in intermediate hydrazine 9 (verified by the reductive cleavage of 1,2-dibenzylhydrazine, see Scheme 1d). 15 Side product 6 was formed by self-condensation of 3 via intermediate imine 5 , 14 while deoxygenated by-product 7 was obtained via a Wolff–Kishner–Huang Minlon reduction. Ni/ meso -Al 2 O 3 -600 is critical for the activation of N 2 H 4 ·H 2 O to generate the active hydrogen species (Ni–[ H ]), 14,16 hydrogenating azine and hydrazone in this reaction.…”

Activation of ammonia and hydrazine by electron rich Fe(ii) complexes supported by a dianionic pentadentate ligand platform through a common terminal Fe(iii) amido intermediate

“…51,73 Even though the homogeneously catalysed disproportionation of hydrazine to ammonia and diazene has previously been reported in a few studies, [74][75][76] the mechanism of this transformation has yet to be studied in great detail. 60,68,77,78 We therefore sought to study the mechanism of the reaction between 1 Tol and hydrazine, both experimentally and theoretically. Two main mechanisms are postulated to explain the formation of 1 Tol -NH 3 and 4 Tol from hydrazine disproportionation mediated by 1 Tol .…”