title: Sandwich complexes based on the "all-metal" Al4 2- aromatic ring.
abstract: We report on novel sandwichlike structures [Al(4)MAl(4)](q-) (q=0-2 and M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W) based on the recently synthesized all-metal aromatic Al(4)(2-) square ring. The sandwichlike structures have two aromatic tetraaluminum square rings which trap a transition-metal cation from either the first, second, or third row. The stability of the anionic sandwichlike complexes towards electron detachment is discussed, and addition of alkali cations is found to stabilize the 2- charged complexes, preventing spontaneous electron detachment. Once the sandwichlike complexes are formed, the Al(4)(2-) square properties remain nearly unchanged; this fact strongly supports the hypothesis that in these complexes the Al(4)(2-) square rings remain aromatic.
authors: Kimika Fakultatea, Euskal Herriko Unibertsitatea, and Donostia International Physics Center (DIPC), P.K. 1072 20080 Donostia, Euskadi, Spain. jm.mercero@ehu.es
authors: Jose M
authors: JM
authors: Mercero
authors: Elena
authors: E
authors: Formoso
authors: Jon M
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authors: Matxain
authors: Leif A
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authors: Jesus M
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