Torsion-wagging tunneling and vibrational states in hydrazine determined from its <i>ab initio</i> potential energy surface

Łodyga, Wiesław; Makarewicz, Jan

doi:10.1063/1.4705267

Cited by 8 publications

(5 citation statements)

References 42 publications

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“…This value is exactly between the value for the N–N bond in neutral hydrazine (CCSD(T)/aug-cc-pVQZ: R N–N = 1.438 Å), and the NN bond in diprotonated diimine (or hydrazine dication), which at the CCSD(T)/aug-cc-pVQZ level of theory is calculated as R NN = 1.230 Å, and very close to the N–N distance in the radical cation of hydrazine (CCSD(T)/aug-cc-pVQZ: R NN = 1.309 Å).…”

Section: Results and Discussionsupporting

confidence: 72%

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

Hill

Bucher

2014

J. Phys. Chem. A

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The properties of the lowest triplet excited states of a series of small molecules containing two or more adjacent heteroatoms have been investigated. High-level coupled cluster and MRCI+Q calculations were employed to probe the properties of the triplet excited states of hydrogen peroxide, hydrazine, hydroxylamine, fluoroamines, oxygen difluoride, hypofluorous acid, chlorine, fluorine, and disulfane. All of the molecules investigated except hydroxylamine are predicted to have bound lowest triplet excited states that are either (π*,σ*) or (σ*,π*) as in H2O2, HOF, OF2, H2S2, Cl2, NH2F, NHF2, or NF3, or are Rydberg states (hydrazine, also H2O2 and H2S2). The heteroatom-heteroatom bond dissociation enthalpies of the triplet states range from very small values as predicted for hydrogen peroxide or fluorine, to BDEs around 8-9 kcal mol(-1) that should allow for an experimental observation of the triplet state, such as in disulfane or monofluoroamine. For all triplet minima investigated except NF3 and F2, CCSD(T) gave results in agreement with the multireference method MRCI+Q, and in excellent agreement with available experimental data (BDEs, ground-state geometries). Due to multireference problems, CCSD(T) does not provide a good description for longer heteroatom-heteroatom distances, and in some cases (e.g., Cl2) it wrongly predicts the presence of a transition state for bond formation on the triplet spin manifold, where the reaction is known experimentally and, as predicted by MRCI+Q, is known to be barrierless. Finally, the (3)Π(u) state of F2 is poorly described by CCSD(T) theory, the equilibrium bond distance is significantly underestimated relative to MRCI+Q, and CCSD(T) places the triplet state above the energy of two fluorine atoms. The T1 diagnostic, frequently used to assess the quality of CCSD(T) calculations, does not appear to provide a valid criterion for the systems studied. The formation of H2O2 on the triplet potential energy hypersurface might possibly open up an additional channel for formation of hydrogen peroxide from two hydroxyl radicals. Due to a low density of states in triplet H2O2, and due to competing formation of water + O((3)P) from a hydrogen-bridged HO···HO triplet radical pair, such a reaction channel probably only can play a role at low temperatures.

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Section: Results and Discussionsupporting

confidence: 72%

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

Hill

Bucher

2014

J. Phys. Chem. A

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“…Hydrazine, which is widely used in organic synthesis and in medicine, demonstrates the influence of unshared electron pairs on the rotation barrier about N-N bond. Its conformational equilibrium includes gauche-form A (global minimum), staggered form B (local TS) and eclipsed form C (main TS); the torsion angle τ in conformer A equals 91.5 • [179][180][181][182]. The energy differences between conformations A-B and A-C (∆G 298 ) are 1.8 kcal/mol and 7.9 kcal/mol respectively (PBE/3ζ, Scheme 1) [183].…”

Section: Hydrazinementioning

confidence: 99%

Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems

Кузнецов

2020

Molecules

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Over the past three decades, carbon nanotubes and fullerenes have become remarkable objects for starting the implementation of new models and technologies in different branches of science. To a great extent, this is defined by the unique electronic and spatial properties of nanocavities due to the ramified π-electron systems. This provides an opportunity for the formation of endohedral complexes containing non-covalently bonded atoms or molecules inside fullerenes and nanotubes. The guest species are exposed to the force field of the nanocavity, which can be described as a combination of electronic and steric requirements. Its action significantly changes conformational properties of even relatively simple molecules, including ethane and its analogs, as well as compounds with C−O, C−S, B−B, B−O, B−N, N−N, Al−Al, Si−Si and Ge−Ge bonds. Besides that, the cavity of the host molecule dramatically alters the stereochemical characteristics of cyclic and heterocyclic systems, affects the energy of pyramidal nitrogen inversion in amines, changes the relative stability of cis and trans isomers and, in the case of chiral nanotubes, strongly influences the properties of R- and S-enantiomers. The present review aims at primary compilation of such unusual stereochemical effects and initial evaluation of the nature of the force field inside nanotubes and fullerenes.

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“…The skew conformer represented in Figure 2, for the

∠

H1─N1─N2─H3 dihedral angle ϕ = 90°, corresponds to calculated values for the minimum energy state, 65–68 and it is even more stable than the trans conformer, which may have the least steric repulsion between the NH 2 moieties, allowing for a simple repulsion model 67 . The dihedral ϕ angle

∠

H1─N1─N2─H3 is the same as the dihedral angle

∠

lp(N)─lp(N), denoting by lp(N) a lone pair of each N atom, see figure 1 of Reference 68.…”

Section: Axial Chirality Of Hydrazine Boranylborane and Ethane Moleculesmentioning

confidence: 86%

“…Hydrazine passes through two transition states, cis (eclipsed) TS1 at ϕ = 0° and trans (staggered) TS2 at ϕ = 180°, in the course of internal rotation about the N─N bond; the ground state conformation corresponds to ϕ = 91.2° 68 . Most accurate CCSD(T) values are in the range 89.6–90°, with a recommended best estimate of 89.6° 66 …”

Section: Axial Chirality Of Hydrazine Boranylborane and Ethane Moleculesmentioning

confidence: 99%

Physical achirality in geometrically chiral rotamers of hydrazine and boranylborane molecules

et al. 2021

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The diagonal components and the trace of tensors which account for chiroptical response of the hydrazine molecule N2H4, that is, static anapole magnetizability and frequency‐dependent electric dipole‐magnetic dipole polarisability, are a function of the ϕ≡∠ H─N─N─H dihedral angle. They vanish for symmetry reasons at ϕ = 0° and ϕ = 180°, corresponding respectively to C2v and C2h point group symmetries, that is, cis and trans conformers characterized by the presence of molecular symmetry planes. Nonetheless, vanishing diagonal components have been observed also in the proximity of ∠ H─N─N─H = 90°, in which the point group symmetry is C2 and hydrazine is unquestionably chiral. In the boranylborane molecule B2H4, assuming the B─B bond in the y direction, the ayy component of the anapole magnetizability tensor approximately vanishes for dihedral angles ∠ H─B─B─H corresponding to chiral rotamers which belong to D2 symmetry. Such anomalous effects have been ascribed to physical achirality of these conformers, that is, to their inability to sustain electronic current densities inducing either anapole moments, or electric and magnetic dipole moments, about the chiral axis connecting heavier atoms, as well as perpendicular directions. In other terms, the structure of certain geometrically chiral rotamers may be such that neither toroidal nor helical flow, which determine chiroptical phenomenology, can take place in the presence of perturbing fields parallel or orthogonal to the chiral axis.

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Torsion-wagging tunneling and vibrational states in hydrazine determined from its ab initio potential energy surface

Cited by 8 publications

References 42 publications

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems

Physical achirality in geometrically chiral rotamers of hydrazine and boranylborane molecules

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Torsion-wagging tunneling and vibrational states in hydrazine determined from its ab initio potential energy surface

Cited by 8 publications

References 42 publications

(π*,σ*), (σ*,π*) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

(π*,σ*), (σ*,π*) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems

Physical achirality in geometrically chiral rotamers of hydrazine and boranylborane molecules

Contact Info

Product

Resources

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(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms