Kuznetsov Aleksey E, Zhai Hua-Jin, Wang Lai-Sheng, Boldyrev Alexander I
Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA.
Inorg Chem. 2002 Nov 18;41(23):6062-70. doi: 10.1021/ic020426+.
Although aromaticity has been observed in inorganic and all-metal species, the concept of antiaromaticity has not been extended beyond organic molecules. Here, we present theoretical and experimental evidence that the 6 -electron tetrapnictogen dianions in Na+Pn42- (Pn = P, As, Sb) undergo a transition from being aromatic to antiaromatic upon electron detachment, yielding the first inorganic antiaromatic Na+Pn4- molecules. Two types of antiaromatic structures were characterized, the conventional rectangular species and a new peculiar quasiplanar rhombus species. Aromaticity and antiaromaticity in the tetrapnictogen molecules were derived from molecular orbital analyses and verified by experimental photodetachment spectra of Na+Pn42-. On the basis of our findings for the tetrapnictogen clusters, we predicted computationally that the organic C4H4- anion also possesses two antiaromatic structures: rectangular and rhombus. Moreover, only the rhombus antiaromatic minimum was found for the radical NC3H4, thus extending the peculiar rhombus antiaromatic structure first uncovered in inorganic clusters into organic chemistry.
尽管在无机和全金属物种中已观察到芳香性，但反芳香性的概念尚未扩展到有机分子之外。在此，我们提供理论和实验证据表明，在Na⁺Pn₄²⁻（Pn = P、As、Sb）中的6电子四氮族元素二价阴离子在电子脱离时会经历从芳香性到反芳香性的转变，从而产生首个无机反芳香性的Na⁺Pn₄⁻分子。表征了两种反芳香性结构，即传统的矩形物种和一种新的奇特准平面菱形物种。四氮族元素分子中的芳香性和反芳香性源自分子轨道分析，并通过Na⁺Pn₄²⁻的实验光电子能谱得到验证。基于我们对四氮族元素簇的研究结果，我们通过计算预测有机C₄H₄⁻阴离子也具有两种反芳香性结构：矩形和菱形。此外，对于自由基NC₃H₄仅发现菱形反芳香性最小值，从而将首次在无机簇中发现的奇特菱形反芳香性结构扩展到有机化学中。
