Realization of an Al≡Al Triple Bond in the Gas‐Phase Na₃Al₂⁻ Cluster via Double Electronic Transmutation

Abstract

The discovery of homodinuclear multiple bonds composed of Group 13 elements represents one of the most challenging frontiers in modern chemistry. A classical triple bond such as N≡N and HC≡CH contains one σ bond and two π bonds constructed from the p orbitals perpendicular to the σ bond. However, the traditional textbook triple bond between two Al atoms has remained elusive. Here we report an Al≡Al triple bond in the designer Na Al cluster predicted in silico, which was subsequently generated by pulsed arc discharge followed by mass spectrometry and photoelectron spectroscopy characterizations. Being effectively Al due to the electron donation from Na, the Al atoms in Na Al undergo a double electronic transmutation into Group 15 elements, thus the Al ≡Al kernel mimics the P≡P and N≡N molecules. We anticipate this work will stimulate more endeavors in discovering materials using Al ≡Al as a building block in the gas phase and in the solid state.

On the Possibility of Using the Jellium Model as a Guide To Design Bimetallic Superalkali Cations

“…Note that the Al−Al bond is remarkably short and its bond index (2.604) is near to 3, implying its triple‐bond nature. It should be mentioned that a similar Al≡Al triple bond has been realized recently in the gas‐phase Na 3 Al 2 − cluster through double electronic transmutation . Moreover, two C 2 v ‐symmetric planar structures are found to be the isomers A and B of Li 3 Al 2 + , which are higher in energy by 16.603 and 48.186 kcal mol −1 , respectively, than the global minimum.…”

“…It should be mentioned that as imilar Al Al triple bond has been realizedr ecently in the gas-phase Na 3 Al 2 À cluster throughd ouble electronic transmutation. [60] Moreover,t wo C 2v -symmetric planar structures are found to be the isomers A and B of Li 3 Al 2 + , which are higher in energy by 16.603a nd 48.186 kcal mol À1 ,r espectively,t han the global minimum. Note that the two Al atoms tend to bind together as an Al 2 unit in all three minimum-energy structures.A lso, it is found that the Li atoms tend to form at riatomic Li 3 subunit in the least favorable structure, B.…”

“…From Table 1, the HOMO-LUMO gaps of the most stable Li 6 Al + ,L i 7 Mg + ,L i 3 Al 2 + ,M g 3 Al + ,a nd Mg 4 Li + cations are in the range 2.28-3.18 eV,w hich are also larger than those of the stable superatoms C 60 and Al 13 À , [56,57] suggesting the chemical stabilitya nd superatomc haracter of theseM Li n + 1 + cations. Besides, as shown in Ta ble S1 (Supporting Information), the gaps of the corresponding local minima of these cations range from 1.41 to 3.40 eV,w hich are still fairly large.…”

All‐Metallic Zn=Zn Double‐π Bonded Octahedral Zn2M4 (M=Li, Na) Clusters with Negative Oxidation State of Zinc

“…Cotton et.al in 1964, [7,8] more and more complexes containing metal-metal multiple bond have been reported and synthesized since then. [9][10][11] Up to now, the CrÀ Cr five-fold bond still remains the record of the highest bond order among the stable species, [12] although the theoretical bond order of the transition metal diatoms can reach six. [2,[13][14][15] However, not all transition-metal atoms can readily form such high multiple bond [6,[16][17][18] and Zinc is one of them.…”

“…The first metal‐metal multiple bonded system of [Re 2 Cl 8 ] 2− was proposed by F. A. Cotton et.al in 1964, more and more complexes containing metal‐metal multiple bond have been reported and synthesized since then . Up to now, the Cr−Cr five‐fold bond still remains the record of the highest bond order among the stable species, although the theoretical bond order of the transition metal diatoms can reach six .…”