Electrostatic potentials of strained systems: nitrocyclopropane

Politzer, Peter; Domelsmith, L. N.; Sjöberg, Per J. R.; Alster, Jack

doi:10.1016/0009-2614(82)83430-1

Cited by 29 publications

(9 citation statements)

References 21 publications

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“…We have found previously that N -0 bonds are typically very sensitive to the choice of basis set [29]. The computed 3-21G N,-0 bond length in V is, however, 1.474 A, in reasonable agreement with the average Ns,3-OS,3 bond distance of 1.463 A [24].…”

Section: Structuressupporting

confidence: 68%

A computational analysis of the electrostatic potentials and relative bond strengths of hydrazine and some of its 1,1‐dimethyl derivatives

Murray

Sukumar

Ranganathan

et al. 1990

Int J of Quantum Chemistry

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We have carried out a computational study of hydrazine and five of its 1,l-dimethyl derivatives, focusing on their electrostatic potentials and relative bond strengths. Our approach has involved the calculation of ab initio self-consistent-field molecular orbital wave functions and molecular properties using the GAUSSIAN 82 system of programs. The electrostatic potentials of the hydrazines possess negative regions of varying sizes and strengths associated with the nitrogens of the a-diamino linkages. Through an analysis of the positions of the most negative potentials of these regions, we have obtained directly the dihedral angles between the nitrogen lone pairs in these systems. Our use of the electrostatic potential to obtain these angles is a direct and general approach, in contrast to indirect procedures used in the past. We find this dihedral angle to be close to 90" in hydrazine, with variations in the substituted hydrazines that depend on the nature of the substituents. A highly polar structure is found for 1-chloromethyl-1 methylhydrazine, which involves a delocalization of electronic charge from the substituted nitrogen towards the CH2CI group. We find that substituents able to withdraw significant amounts of electronic density from the central nitrogen lone pair regions, either through resonance or by induction, have a slight bond strengthening effect on the central N-N bond. This is attributed to a decrease in the repulsion between the weakened nitrogen lone pair regions. The difficulties encountered in seeking the controlled oxidation of hydrazine to nitro derivatives may be due, in part, to the fact that two factors which would favor this, highly negative nitrogen potentials and strong N-N bonds, are opposing in nature.

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Section: Structuressupporting

confidence: 68%

A computational analysis of the electrostatic potentials and relative bond strengths of hydrazine and some of its 1,1‐dimethyl derivatives

Murray

Sukumar

Ranganathan

et al. 1990

Int J of Quantum Chemistry

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“…Figure 1 compares the topology of (r) and V nuc (r) of cyclopropane, oxirane, and spiropentane. As expected, the so-called bond paths in cyclopropane are curved outward, which has been interpreted as a sign of bond strain [70], quantified later [71] by means of a bond deviation index. The topology of V nuc (r) shows the same number and connectivity of critical points for exactly the same nuclear configuration.…”

Section: Resultssupporting

confidence: 59%

Geometrically faithful homeomorphisms between the electron density and the bare nuclear potential

Popelier

Brémond²

2009

Int J of Quantum Chemistry

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ABSTRACT:The topology of the nuclear potential, V nuc (r), of just over 130 molecules and molecular complexes is investigated and compared with the topology of the electron density (r). As nuclear positions are kept fixed in this comparison, this work screens for geometrically faithful homeomorphisms between (r) and V nuc (r). In this set of molecules spanning simple inorganic moieties, strained (and cyclic) hydrocarbons, (fused) aromatics, boranes, van der Waals complexes, water clusters, and a few biomolecules, about 70% of the systems show this homeomorphism. A simple analytical formula is derived, expressing the position of a (3,Ϫ1) critical point in any diatomic as a function of the participating atomic numbers. The topology of V nuc (r) at one location of a molecule can sensitively depend on the presence or absence of a substituent far away from this location.

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“…A similar effect of the nitro group has been noted on cyclopropane. 30 The electric-field plots suggest that, a t least at large separations, an incoming electrophile would experience a net force directing it toward the edges and faces of cubane and the oxygens of the nitro group of the nitrated cubanes.…”

Section: Electrostatic Potential and Electric Fieldmentioning

confidence: 99%

Some methods and applications of electron density distribution analysis

1987

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Accurate and effkient integration of the electron density function over arbitrary regions has been previously achieved by exploiting a separation of variables. Recently, a computer program has been written that calculates p, P p , and V2p in an expeditious fashion, taking advantage of the separation of variables in the electron density function. Accurate integrations of V2p over arbitrary regions can also be accomplished. The structure of the program is suited especially to vector processors. As a result of the efficiencies of these programs, functions of the electron density, such as the density itself, the surrounding electrostatic potential, V p , and V2p have been calculated in three dimensions. Results of calculations for nitrated cubanes are presented illustrating how the effects of the nitro groups are manifested in the electron density and associated properties.The electron distribution of a molecule and its change during chemical reaction are fundamental to understanding molecular structure, chemical reactivity, and molecular interactions. Indeed, the language of chemistry is heavily couched in terms that, either implicitly or explicitly, infer something of the electron density. So, for example, terms such as bonds, lone-pairs, electron-rich, electron-poor, electron-donating, electronwithdrawing, conjugation, polarization, and charge-transfer, to name a few, bring to mind pictures that presume some features of the electron distribution in a molecule. It is the purpose of our investigations to compare these simple and useful pictures with electron distributions obtained from a b initio molecular orbital calculations. In this fashion, a firm theoretical basis for some of the fundmental concepts of chemistry can be established and more precise criteria developed for classifying and, ultimately, predicting chemical phenomenology. Additionally, we hope to develop efficient computational techniques for analyzing electron distrubitions and calculating molecular interactions.Many approaches have been devised for analyzing electron distributions. Bader has developed a topological model that divides the *To whom all correspondence should be addressed. molecule into atomic regions, each of which obeys the same quantum mechanics as the whole molecule.' In the sense that each of the atomic regions is quantum mechanically meaningful and that chemical bonds, rings, and cages can be precisely defined without reference to arbitrary standards, the topological model is superior to other approaches for characterizing electron density distributions. Underlying this approach are the vector v p and the scalar quantity V'p.The vector quantity v p is primarily used for determining atoms in molecules. The surfaces enclosing atoms in molecules are those surfaces through which the flux of v p is zero. Determination of these zero flux surfaces defines a volume of electron density that "belongs" to the enclosed atom. Properties of atoms in molecules such as: atomic charge and higher multipoles, atomic kinetic, potential, and total en...

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Electrostatic potentials of strained systems: nitrocyclopropane

Cited by 29 publications

References 21 publications

A computational analysis of the electrostatic potentials and relative bond strengths of hydrazine and some of its 1,1‐dimethyl derivatives

A computational analysis of the electrostatic potentials and relative bond strengths of hydrazine and some of its 1,1‐dimethyl derivatives

Geometrically faithful homeomorphisms between the electron density and the bare nuclear potential

Some methods and applications of electron density distribution analysis

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