Ab Initio Study of Interactions in Hydrazine Clusters of One To Four Molecules:  Cooperativity in the Interaction

Abstract

Computations on systems consisting of up to four hydrazine molecules were performed by using the HF, DFT/B3LYP, and MP2 methods with the 6-31+G* basis set. The dimer was found to exhibit two minima with very similar interaction energies (ca. 20−22 kJ/mol). The overall minimum at the MP2 level corresponds to a structure of C 1 symmetry involving a hydrogen bond at about 2.2 Å in addition to several other N···H contacts at longer distances. The other minimum found possesses C 2 symmetry and involves two hydrogen bonds, also at ca. 2.2 Å. A transition state about 4−6 kJ/mol less stable than the previous minima was also found. The trimer occurs in several structures that correspond to minima with slight energy differences among them; hydrogen bond distances are shorter than those in the dimer as a result of the stronger interactions between molecules. The contribution of cooperative phenomena to the interaction energy is quite significant (it amounts to as much as 12% of the overall interaction energy). The two minima of the tetramer behave similarly to those of the trimer; the contribution of nonadditive terms accounts for 10% of the overall interaction energy.

Ethical issues in cardiovascular publications: Observations during 25 years as an editor

“…There are four N … H contacts and the shorter distances compared to other clusters in 4B , by which it can be speculated that the intensities of interactions in 4B may be the strongest. This phenomenon is contrary to that obtained by Cabaleiro‐Lago for the hydrazine cluters 11, in which the trimer's cooperativity is stronger than the tetramer's.…”

“…A complete understanding of clusters or condense phases is of course impossible with knowledge only of pairwise additive interaction. The close contact of a large number of molecules brings about cooperative phenomena as each molecule is influenced by more than one of its neighbors 10, 11, which is reflected with changes of some properties, such as hydrogen bond intensity increase and the frequency shift with an increase in cluster size. So, properly characterizing these phenomena are crucial to understanding the behavior of clusters.…”

Electronic structure and second hyperpolarizability of M(NA2)2 (M = Be, Mg, Ca; A = H, Li, Na) complexes

“…The optimized geometry of hydrazine is in the gauche form which is consistent with the previous theoretical results [42] [43]). The present B3LYP and MP2 results of those structural parameters are in good conformity with the earlier theoretical results [44] obtained for the 6-311++G(2d,2p) calculated results. The <HNH angle in hydrazine corresponds to the ideal tetrahedral (sp 3 ) hybridization of N atoms.…”

Mechanism for the reaction of 2‐naphthol with N‐methyl‐N‐phenyl‐hydrazine suggested by the density functional theory investigations

“…The chemistry of hydrazines has extensively been studied experimentally [1][2][3] and theoretically [4][5][6][7][8][9][10][11][12] since the late 19th century as it is widely applied in preparation of azo dyes, [13] pharmaceuticals, [14][15][16][17][18] agrochemicals, rocket fuels, and so on.…”