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New insight into the nature of electron delocalization: The driving forces for distorting the geometry of stilbene-like species
Yu, ZH; Peng, XQ
2001-09-20
Source PublicationJOURNAL OF PHYSICAL CHEMISTRY A
ISSN1089-5639
Volume105Issue:37Pages:8541-8553
AbstractTo understand the nature of electron delocalization while questioning the abnormally large torsional angle theta of N-phenylmethylene-3-pyridineamine (6), we greatly improved our new program for energy partitioning. Meanwhile, the crystal structures of N-phenylmethylene-2-thiazoleamine (1a) and N-(4-nitro-phenyl)methylene2-thiazoleamine (1b) were determined using X-ray diffraction. As shown by the optimized geometries of the molecules, such as 1a, 1b, (4-NO2-Ph)-CH=N-2-pyrimidyl, (4-NO2-Ph)-CH=N-2-pyridyl, and 6 with HF, DFT, MP2, and AM1, the results that d(2)(E-e(theta))/d\theta\(2) > 0.0 for total electronic energy and d(2)(E-N(theta))/d\theta\(2) < 0.0 for nuclear repulsion and d(E-e(theta =42 degrees))/d\theta\(2) = 0.0 are not an artifact of a given optimized method, nor a distinct feature of a special molecule. As shown by the energy partitions, the and nonbonded sigma-sigma interactions between fragments are always destabilization, and it is the nonbonded sigma-sigma interaction, rather than the pi-pi interaction, that distorts stilbene-Like species away from their planar geometry. The destabilizing EX interactions between fragments is basically stabilization as far as its total effect on whole electronic state is considered. Correspondingly, the stabilizing CT interaction is practically destabilization. Thus, at the planar geometry, it is due to d(CT)/d(r) < 0.0, d(EX)/d(r) <0.0, or their sum d(CT)/d(r) + d(EX)/d(r) < 0.0, where r = r(ab) or r(14), to shorten the length r(14) of the bond C-1-N-4 as well as to reduce the distance r(ab), between fragments. A stilbene-like species has to distort itself away from its planar geometry in order to maintain its lowest total electronic energy E-e as far as possible when the attractive force d(E-e(theta))/ d(rab) > 0.0 is not large enough to balance the resistance force d(V-ab)/d(r(ab)) < 0.0. Resistances to the distortion arise from the destabilizing pi-sigma interaction and from the dE(N)(theta)/d\0\ > 0.0. At a geometry with about theta = 52 degrees, d(DeltaE(theta))/d\theta\ = 0 is a compromise between the nonbonded sigma-sigma and ar-a interactions, and it is approximately in accord with the d(E-e(theta =42 degrees))/d\theta\ = 0.0 obtained from standard Gaussian 98 program.
Indexed BySCI
Language英语
WOS IDWOS:000171032500022
PublisherAMER CHEMICAL SOC
Citation statistics
Cited Times:19[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.iccas.ac.cn/handle/121111/77400
Collection中国科学院化学研究所
Corresponding AuthorYu, ZH
AffiliationChinese Acad Sci, Inst Chem, State Key Lab Struct Chem Unstable & Stable Speci, Beijing 100080, Peoples R China
Recommended Citation
GB/T 7714
Yu, ZH,Peng, XQ. New insight into the nature of electron delocalization: The driving forces for distorting the geometry of stilbene-like species[J]. JOURNAL OF PHYSICAL CHEMISTRY A,2001,105(37):8541-8553.
APA Yu, ZH,&Peng, XQ.(2001).New insight into the nature of electron delocalization: The driving forces for distorting the geometry of stilbene-like species.JOURNAL OF PHYSICAL CHEMISTRY A,105(37),8541-8553.
MLA Yu, ZH,et al."New insight into the nature of electron delocalization: The driving forces for distorting the geometry of stilbene-like species".JOURNAL OF PHYSICAL CHEMISTRY A 105.37(2001):8541-8553.
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