Ab initio quantum chemical computations of substituent effects on triaziridine strain energy and heat of formation

Peverati, Roberto; Siegel, Jay S.; Baldridge, Kim K.

doi:10.1039/b816782f

Cited by 10 publications

(3 citation statements)

References 82 publications

(81 reference statements)

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“…However,i ns ome cases their structures remainu nknown. The effect of substituents on strained molecules has been investigated, as (de)stabilization of the molecule upon substitution by various types of common electron-withdrawing or -donating substituents can occur, [13,14] and the substituents can affect the strain energy,h eat of formation, [13,15] or dissociation energies. [16] Since 2010, our group has been engaged in the accurate determination of the structure of systems with bridged bicyclic rings, and so far 2-aminonorbornane, [17] tropinone, [18] scopoline, [19] and even the hydrated complex tropinone···H 2 O [20] have been studied.…”

Section: Introductionmentioning

confidence: 99%

Structural Distortion of the Epoxy Groups in Norbornanes: A Rotational Study of exo‐2,3‐Epoxynorbornane

et al. 2015

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Exo-2,3-epoxynorbornane is studied in the gas phase by pulsed jet Fourier transform microwave spectroscopy in the 4-18 GHz region. Six isotopologues were observed and characterized in their natural abundance. The experimental substitution and effective structures were obtained. Comparison with the structure of norbornane shows significant differences in several bond lengths and valence angles upon introduction of the epoxy group. All the work is supported by quantum chemical calculations.

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Section: Introductionmentioning

confidence: 99%

Structural Distortion of the Epoxy Groups in Norbornanes: A Rotational Study of exo‐2,3‐Epoxynorbornane

et al. 2015

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“…Ring strain represents an important and useful paradigm in chemistry, the release of which provides the driving force for many proposed reaction mechanisms. Despite being predominately associated with organic systems, considerable attention has been devoted to determining the strain energies of both organic – and inorganic – compounds. While not an experimental observable, numerous attempts to quantify these energetic values remains a hotly debated topic, none so more than for the deceptively simple hydrocarbon cyclopropane. – Evaluations frequently employ chemical equations, which attempt to balance all structural and stereoelectronic features present within a ring, except the strain itself.…”

Section: Introductionmentioning

confidence: 99%

How Strained are Carbomeric-Cycloalkanes?

et al. 2010

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The ring strain energies of carbomeric-cycloalkanes (molecules with one or more acetylene spacer units placed into carbon single bonds) are assessed using a series of isodesmic, homodesmotic, and hyperhomodesmotic chemical equations. Isodesmic bond separation reactions and other equations derived from the explicitly defined hierarchy of homodesmotic equations are insufficient for accurately determining these values, since not all perturbing effects (i.e., conjugation and hyperconjugation) are fully balanced. A set of homodesmotic reactions is proposed, which succeeds in balancing all stereoelectronic effects present within the carbomeric rings, allowing for a direct assessment of the strain energies. Values calculated from chemical equations are validated using an increment/additivity approach. The ring strain energy decreases as acetylene units are added, manifesting from the net stabilization gained by opening the C-CH(2)-C angle around the methylene groups and the destabilization arising from bending the C-C identical withC angles of the spacer groups. This destabilization vanishes with increasing parent ring size (i.e., the angle distortion is less in the carbomeric-cyclobutanes than in the carbomeric-cyclopropanes), leading to strain energies near zero for carbo(n)-cyclopentanes and carbo(n)-cyclohexanes.

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“…Angular strain is well studied and appears to follow Bent’s Rule, which states that even small changes in hybridization can yield drastic differences in chemical properties, like RSE. This has been reflected in a variety of 3-membered rings ranging from hydrocarbon to heavy-element containing heterocycles. , Otherwise, RSE research has centralized around complex bicyclic compounds (norbornanes, adamantanes, tetrahedranes, cubanes), which have a combination of the different strain types. ,,, Studies regarding substituent effects have been limited to simple side chains and are usually either focused on angular and/or highly strained rings. ,− …”

Section: Introductionmentioning

confidence: 99%

Substituent Effects on Torsional Strain in Cyclopentene Derivatives: A Computational Study

et al. 2023

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Density functional theory calculations were used to create a library of ring strain energies (RSEs) for 73 cyclopentene derivatives with potential use as monomers for ring-opening metathesis polymerization (ROMP). An overarching goal was to probe how substituent choice may influence torsional strain, which is the driving force for ROMP and one of the most understudied types of RSEs. Potential trends investigated include substituent location, size, electronegativity, hybridization, and steric bulk. Using traditional and recently developed homodesmotic equations, our results show that the size and substitution (bulk) of the atom directly bonded to the ring have the greatest influence on torsional RSE. A complex interplay between bond length, bond angle, and dihedral angle dictates the relative eclipsed conformations between the substituent and its neighboring hydrogens and was found to be responsible for the notable differences in RSEs. Furthermore, substituents placed on the homoallylic position resulted in higher RSEs than the same substituent placed on the allylic position due to increased eclipsing interactions. Different levels of theory were also assessed, and it was determined that consideration of electron correlation in calculations increased RSEs by ∼2–5 kcal mol–1. Further increasing the level of theory did not significantly change RSEs, indicating that the increased computational cost and time may not be necessary for improved accuracy.

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Ab initio quantum chemical computations of substituent effects on triaziridine strain energy and heat of formation

Cited by 10 publications

References 82 publications

Structural Distortion of the Epoxy Groups in Norbornanes: A Rotational Study of exo‐2,3‐Epoxynorbornane

Structural Distortion of the Epoxy Groups in Norbornanes: A Rotational Study of exo‐2,3‐Epoxynorbornane

How Strained are Carbomeric-Cycloalkanes?

Substituent Effects on Torsional Strain in Cyclopentene Derivatives: A Computational Study

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