Sandwich Complexes Based on the “All‐Metal” Al₄²⁻ 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.

All‐Metal Aromatic Sandwich Binuclear Complexes: Electronic Structures, Aromaticity and Interactions with Hydrogen via Multicenter Bonds

“…The selected bond lengths and distances(Å) parameters are shown in Table . In fact the bond length of two Al atoms in the pristine Al 4 2− square is 2.63 Å, which is slightly larger than 2.59 Å calculated by Mercero et al, but it changes between 2.60‐2.75 Å in the complexes being considered. The bond distance between two Al atoms increases slightly when we go from the right of the third subgroup IIIB to the fifth subgroup VB and then down from the fourth period to the sixth period in the periodic table.…”

‘All-Metal’ Aromatic Sandwich Molecules: An Electronic Structure and Transport Study

“…DFT hybrid functional B3LYP [27][28][29][30] was used for the study along with 6-31++G * * basis-set for all atoms except Molybdenum for which Lanl2DZ basis-set and pseudopotentials were employed. The isolated molecules are all taken in nonmagnetic singlet states as these states are the low energy ground states [6][7][8] and electronic transport studies are performed for these systems. The electronic structure studies were also performed using PBE1PBE 31 functional and 6-31++G * * basis-set and the distances, nature of the molecular orbitals were all found to be very similar, only the molecular orbital energies were slightly different.…”

“…[1][2][3][4] Unlike traditional organic aromatics, many 'allmetal clusters' with aromatic properties, i.e., metallaromatic clusters/molecules have been discovered during the last decade. [5][6][7][8][9] Though the catalytic ability of all-metal aromatic complexes is found to be strong, 10 11 the electronic transport properties have never been explored earlier. The electronic transport of these systems are likely to be interesting due to aromaticity, in-plane delocalization of electrons and their inherent similarities to metal atomic chains which are known to show exotic electron transport properties.…”

Neutral all metal aromatic half-sandwich complexes between alkaline earth and transition metals: an ab initio exploration

“…al synthesized all metal aromatic sandwich compound [Sb 3 Au 3 Sb 3 ] 3− where Au 3 ring is sandwiched by two cyclo-Sb 3 rings [27]. It is worth mentioning here that previously such all metal sandwich complexes have been predicted theoretically [28][29][30][31][32][33][34][35].…”