All-Metal Antiaromaticity in Sb-4-Type Lanthanocene Anions

摘要

Antiaromaticity, as introduced in 1965, usually refers to monocyclic systems with 4n pi electrons. This concept was extended to all-metal molecules after the observation of Li3Al4- in the gas phase. However, the solid-phase counterparts have not been documented to date. Herein, we describe a series of all-metal antiaromatic anions, [Ln((4)-Sb-4)(3)](3-)(Ln=La, Y, Ho, Er, Lu), which were isolated as the K([2.2.2]crypt) salts and identified by single-crystal X-ray diffraction. Based on the results obtained from the chemical bonding analysis, multicenter indices, and the electron-counting rule, we conclude that the core [Ln((4)-Sb-4)(3)](3-) fragment of the crystal has three locally pi-antiaromatic Sb-4 fragments. This complex represents the first locally pi-antiaromatic all-metal system in the solid state, which is stabilized by interactions of the three pi-antiaromatic units with the central metal atom.