INVERSION PROCESSES IN PHOSPHINES AND THEIR RADICAL CATIONS : WHEN IS A PSEUDO-JAHN-TELLER EFFECT OPERATIVE?
INVERSION PROCESSES IN PHOSPHINES AND THEIR RADICAL CATIONS : WHEN IS A PSEUDO-JAHN-TELLER EFFECT OPERATIVE?
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膦及其自由基阳离子的反转过程：伪 JAHN-Teller 效应何时起作用？
DOI：
10.1021/jp981083x
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发表时间：
1998
影响因子：
2.9
通讯作者：
M. Nguyen
中科院分区：
文献类型：
--
作者：
Steven Creve;M. Nguyen
采用高水平从头算分子轨道和密度泛函理论计算方法，研究了取代膦（R3P）及其自由基阳离子的转化过程。特别注意的是对反转机制的理解。而在PH3和甲基衍生物中只存在经典的顶点反转，卤代膦在大多数中性物质中通过C2v t型过渡结构反转。a1 ‘⊗e ’混合导致D3h到C2v t型过渡结构的伪jahn−Teller效应被证实是导致边缘反转的原因。这种效应在PH3的至少两个H原子被卤素原子取代时起作用，并且在f衍生物中表现得最大。伪jt效应在f> Cl > Br的量级上减小。在自由基阳离子中，反转势垒持续而显著地降低，在PCl3•+和PBr3•+中，伪jahn−Teller效应几乎消失，边缘向内延伸。
The inversion processes in substituted phosphines (R3P) and their radical cations have been investigated in detail using high-level ab initio molecular orbital and density functional theory calculations. Particular attention has been paid to the understanding of the inversion mechanism. While in PH3 and methyl derivatives only the classical vertex inversion exists, halogenated phosphines invert through C2v T-shaped transition structures in most neutral species. The pseudo-Jahn−Teller effect in which an a1‘ ⊗ e‘ mixing leads a D3h to a C2v T-shaped transition structure is confirmed to be responsible for the edge inversion. This effect is operative upon substitution of, at least, two H atoms of PH3 by halogen atoms and appears to be largest in F-derivatives. The pseudo-JT effect is reduced in the order F > Cl > Br. In radical cations, the inversion barriers are consistently and substantially reduced, in such a way that in PCl3•+ and PBr3•+ the pseudo-Jahn−Teller effect virtually disappears and the edge inve...