All‐Metal Antiaromaticity in Sb₄‐Type Lanthanocene Anions

Abstract

Antiaromaticity, as introduced in 1965, usually refers to monocyclic systems with 4n π electrons. This concept was extended to all-metal molecules after the observation of Li3 Al4 (-) 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(η(4) -Sb4 )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(η(4) -Sb4 )3 ](3-) fragment of the crystal has three locally π-antiaromatic Sb4 fragments. This complex represents the first locally π-antiaromatic all-metal system in the solid state, which is stabilized by interactions of the three π-antiaromatic units with the central metal atom.

Peculiar All‐Metal σ‐Aromaticity of the [Au2Sb16]4− Anion in the Solid State

“…In this work, the applicability of this concept is extended towards solid-state compounds by demonstrating au nique example of as torable compound, which was isolated as astable [K([2.2.2]crypt)] + salt, featuring a[ Au 2 Sb 16 ] 4À cluster core possessing two all-metal aromatic AuSb 4 fragments with six delocalized s electrons each (n = 1). [4] The [U@Bi 12 ] 3À anion with similar geometry was reported very recently by Dehnen and co-workers. [2] Theconcepts of p aromaticity/antiaromaticity were primarily used to explain chemical bonding in organic compounds.…”

“…[2] Theconcepts of p aromaticity/antiaromaticity were primarily used to explain chemical bonding in organic compounds. [4] The [U@Bi 12 ] 3À anion with similar geometry was reported very recently by Dehnen and co-workers. [4] The [U@Bi 12 ] 3À anion with similar geometry was reported very recently by Dehnen and co-workers.…”

“…[6] Fort he first time,t he saromaticity concept was shown to be applicable to small alkali metal and alkaline earth metal clusters. Hence,the 6s-electron aromatic fragments found in the [Au 2 Sb 16 ] 4À cluster in this study expand the family of storable aromatic metal clusters thus solidifying usefulness of the s-aromaticity concept in the solid state.Thet itle complex [Au 2 Sb 16 ] 4À (1), crystallizes in the form of [K([2.2.2]crypt)] 4 ·1·4 en ( Figure S1 and Table S1), was isolated from an ethylenediamine (en) solution of K 3 Sb 7 , Au(PPh 3 ) Ph,and 4,7,13,16,21,hexacosane ([2.2.2]crypt;e xperimental details can be found in the Supporting Information). [8][9][10][11] Fora ll all-metal aromatic fragments that have been synthesized in the solid state up to date,t here were only two delocalized electrons responsible for the s-aromaticity of the compounds,asexemplified by the cases of Pd 3 + ,Au 3 + ,and TiSn 2 clusters.…”

“…Thet itle complex [Au 2 Sb 16 ] 4À (1), crystallizes in the form of [K([2.2.2]crypt)] 4 ·1·4 en ( Figure S1 and Table S1), was isolated from an ethylenediamine (en) solution of K 3 Sb 7 , Au(PPh 3 ) Ph,and 4,7,13,16,21,hexacosane ([2.2.2]crypt;e xperimental details can be found in the Supporting Information). As shown in Figure 1, complex 1 has ar od-like shape and two Au atoms inlaid on the surface of the Sb 16 polyanion framework possessing quasi-C 2 point group symmetry.…”

Computational insights into the concomitant changes of hollow interior evolution in [SbnAunSbn]m (n=3, 4, 5, 6; m= -3, -2, -1, -2) complex

“…More negative NICS values suggest more aromatic system characteristic. 56 The NICS value of the title species at the ring center [NICS (0) 58 The NICS (1) of cyclo-Sb n is different with NICS (-1), suggesting that cyclo-Au n has an influence on cyclo-Sb n . The magnitude of NICS (0) and NICS (1) obeyes the following order: cyclo-Sb 5 > cyclo-Sb 6 > cyclo-Sb 3 > cyclo-Sb 4 , consistent with the elongation of the computed Sb-Sb bond distance.…”