On the structure and stability of electron deficient species derived from [Cr(CO)3(arene)]
On the structure and stability of electron deficient species derived from [Cr(CO)3(arene)]
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DOI：
10.1016/s0022-328x(00)00345-4
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发表时间：
2000-08-11
影响因子：
2.3
通讯作者：
Dyson, PJ
中科院分区：
文献类型：
--
作者：
McGrady, JE;Dyson, PJ
电子轰击电离质谱已被用于研究[Cr（CO）（3）（arene）]，芳烃= C6 H6，C6 H4 Me 2 - 1，4，C6 H2 Me 3 - 1，2，4.5和C6 Me 6。CO配体的连续损失导致产生缺电子络合物[Cr（CO）（3-x）（C6 H6）]（+）（其中x=0至3）。这些物种使用近似密度泛函理论的分析表明，CO配体的损失稳定高自旋态，效果更显着的阳离子物种比在他们的中性对应物。高自旋态也往往比低自旋态具有更对称的结构。第二CO离解能的计算值低于第一或第三CO离解能，这与通过电子碰撞电离质谱法获得的气相数据一致，其一致地显示[Cr（CO）（C6 H6）]（+）的峰比[Cr（CO）（2）（C6 H6）]（+）的峰更强。第二CO配体的损失导致从双峰到六重基态的转变，并且所得的大量结构重排可能是导致低解离能的原因。(C)2000 Elsevier Science S.A. All rights reserved.
Electron impact ionisation mass spectrometry has been used to study [Cr(CO)(3)(arene)], arene = C6H6, C6H4Me2-1,4, C6H2Me3-1,2,4.5 and C6Me6. Successive loss of CO ligands results in the production of electron-deficient complexes [Cr(CO)(3-x)(C6H6)](+) (where x=0 to 3). Analysis of these species using approximate density functional theory indicates that the loss of CO ligands stabilises high-spin states, the effect being more marked in the cationic species than in their neutral counterparts. The high-spin states also tend to have more symmetric structures than their low-spin counterparts. The calculated value of the second CO dissociation energy is lower than either the first or third, consistent with gas-phase data obtained by electron impact ionisation mass spectrometry, which consistently show more intense peaks for the [Cr(CO)(C6H6)](+) than for [Cr(CO)(2)(C6H6)](+). The loss of the second CO ligand results in a transition from a doublet to a sextet ground state, and the resultant substantial structural rearrangements may be responsible for the anomalously low dissociation energy. (C) 2000 Elsevier Science S.A. All rights reserved.