Corminboeuf Clémence, Schleyer Paul von Ragué, King R Bruce
Department of Chemistry and Center for Computational Chemistry, University of Georgia, Georgia, Athens, Georgia 30602, USA.
Chemistry. 2007;13(3):978-84. doi: 10.1002/chem.200601037.
Recently, the sigma-aromaticity model proposed for cyclopropane by Dewar was employed to account for the stability of Group 8 trinuclear metal-carbonyl compounds [M(3)(CO)(12)] (M=Fe, Ru, Os). This paper further examines this hypothesis and provides the first quantitative evidence for the sigma-aromatic/antiaromatic nature of the [M(3)(CO)(12)]/[M(4)(CO)(16)] species based on structural and nucleus-independent chemical-shift analysis. In addition, the extent of electron delocalization in tetrahedral [M(4)(CO)(14)] and butterfly [M(4)(CO)(15)] is analyzed and compared to prototype cycloalkanes. While remarkable analogies exist between metal-carbonyls and cycloalkanes, transition metals provide additional overlap possibilities that affect both the ring strain and the magnetic properties of metal-carbonyl rings and cages.
最近，杜瓦提出的用于环丙烷的σ-芳香性模型被用于解释第8族三核金属羰基化合物[M₃(CO)₁₂]（M = Fe、Ru、Os）的稳定性。本文进一步检验了这一假设，并基于结构和核独立化学位移分析，为[M₃(CO)₁₂]/[M₄(CO)₁₆]物种的σ-芳香/反芳香性质提供了首个定量证据。此外，还分析了四面体[M₄(CO)₁₄]和蝶形[M₄(CO)₁₅]中电子离域的程度，并与原型环烷烃进行了比较。虽然金属羰基化合物和环烷烃之间存在显著的相似性，但过渡金属提供了额外的重叠可能性，这会影响金属羰基环和笼的环张力和磁性。
