Ab initio through space/bond interaction analysis on the stereoelectronic effect by modifying the exponents of the basis set

Abstract

ABSTRACT:The concept of the stereoelectronic effect has been widely used for the elucidation of organic reaction mechanisms. However, a detailed analysis of this effect has not been developed, especially at the level of the ab initio molecular orbital method. In the present article, the through spacerbond interaction analysis was applied to the stereoelectronic effect at the level of the ab initio molecular orbital method. To obtain a reliable result for the through spacerbond interaction analysis, we introduced a novel procedure to cut off a specific through spacerbond interaction, that is, cutting off a specific integral is performed by increasing the absolute magnitude of the exponent in a Gaussian function. By this procedure, we can easily find a balance in cutting off the nuclear᎐electron attractions, the nuclear᎐nuclear repulsions, and the electron᎐electron repulsions. By using the above-mentioned procedure, we carried out a through spacerbond interaction analysis to the stereoelectronic effect for aminomethanol as a model molecule. As a result, the diagonal terms for the electron transfer play a more important role than do the off-diagonal terms. Since the diagonal term corresponds to the conventional steroelectronic effect, the obtained result is in accordance with the conventional model for the stereoelectronic effect. This result may give a novel insight into the stereoelectronic effect.

Ab Initio MO Analysis of Interaction Paths between Radicals in Ferromagnetic Organic Systems

“…33 TS/TB interaction analysis [34][35][36][37][38][39] was developed to analyze orbital interactions in a molecule quantitatively at the level of the ab initio MO method. We can estimate the contribution of specific orbital interactions to total energy by deleting the interactions in question.…”

NBO‐based CI/MP through‐space/bond interaction analysis and its application to stereoelectronic effects in SN2 reactions

“…The concept of TS/TB interactions divides the numerous types of intramolecular interactions into only two types—that is, interactions through space and those through bond 6—and has been applied to various fields of chemistry 7. TS/TB analysis 8–10 was developed to elucidate stereoelectronic effects in organic compounds quantitatively 8, and has been applied to rotational barriers 9, conjugation effects 10, and so on. This treatment enables us to examine specific orbital interactions by modifying the exponents in the basis functions corresponding to the interactions.…”

Nonlinear optical properties of polydiacetylene with donor-acceptor substitution block

“…26 By using this technique, we can estimate the contribution from individual TS/TB interac-tion, and it has already been applied to the analysis of the enhancement of the NLO effect in zwitterionic molecules, 27 the phenomena of extraordinarily long C-C distance in photoisomers, 31 stereoelectronic effects in S N 2 reaction, 32 and ͓3+2͔ annulation based on Brook rearrangement. We have developed a method to analyze the TS/TB interactions quantitatively at the ab initio level.…”

“…[14][15][16][17][18][19][20] Especially, for the substituent effects in PDA derivatives, Yoshimura studied the enhancement of the first hyperpolarizability ͑␤͒ in substituted PDA by analyzing the shapes of the highest occupied molecular orbital ͑HOMO͒ and the lowest unoccupied molecular orbital ͑LUMO͒. 25 In addition to the chain length dependence, we examined the relationship between NLO effects and the orbital interaction by the through-space/bond ͑TS/TB͒ interaction analysis 26 for estimating the magnitude of the influence on TB interaction. 22 In the present work, we examine the chain length dependence on molecular hyperpolarizabilities of substituted PDAs and the relationship between ␤͑␥͒ values and the size of donor-acceptor building block at ab initio levels.…”