The Al=Al double bond is elusive in chemistry. Herein we report the results obtained via combined photoelectron spectroscopy and ab initio studies of the LiAl2H4−cluster that confirm the formation of a conventional Al=Al double bond. Comprehensive searches for the most stable structures of the LiAl2H4−cluster have shown that the global minimum isomer I possesses a geometric structure which resembles that of Si2H4, demonstrating a successful example of the transmutation of Al atoms into Si atoms by electron donation. Theoretical simulations of the photoelectron spectrum discovered the coexistence of two isomers in the ion beam, including the one with the Al=Al double bond.
The Al=Al double bond is elusive in chemistry. Herein we report the results obtained via combined photoelectron spectroscopy and ab initio studies of the LiAl2H4−cluster that confirm the formation of a conventional Al=Al double bond. Comprehensive searches for the most stable structures of the LiAl2H4−cluster have shown that the global minimum isomer I possesses a geometric structure which resembles that of Si2H4, demonstrating a successful example of the transmutation of Al atoms into Si atoms by electron donation. Theoretical simulations of the photoelectron spectrum discovered the coexistence of two isomers in the ion beam, including the one with the Al=Al double bond.
more » « less- NSF-PAR ID:
- 10047359
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie
- Volume:
- 129
- Issue:
- 52
- ISSN:
- 0044-8249
- Page Range / eLocation ID:
- p. 16820-16823
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract -
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 Na3Al2−cluster predicted in silico, which was subsequently generated by pulsed arc discharge followed by mass spectrometry and photoelectron spectroscopy characterizations. Being effectively Al2−due to the electron donation from Na, the Al atoms in Na3Al2−undergo a double electronic transmutation into Group 15 elements, thus the Al2−≡Al2−kernel mimics the P≡P and N≡N molecules. We anticipate this work will stimulate more endeavors in discovering materials using Al2−≡Al2−as a building block in the gas phase and in the solid state.
-
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 Na3Al2−cluster predicted in silico, which was subsequently generated by pulsed arc discharge followed by mass spectrometry and photoelectron spectroscopy characterizations. Being effectively Al2−due to the electron donation from Na, the Al atoms in Na3Al2−undergo a double electronic transmutation into Group 15 elements, thus the Al2−≡Al2−kernel mimics the P≡P and N≡N molecules. We anticipate this work will stimulate more endeavors in discovering materials using Al2−≡Al2−as a building block in the gas phase and in the solid state.
-
Abstract Aluminyl anions are low‐valent, anionic, and carbenoid aluminum species commonly found stabilized with potassium cations from the reaction of Al‐halogen precursors and alkali compounds. These systems are very reactive toward the activation of
σ ‐bonds and in reactions with electrophiles. Various research groups have detected that the potassium atoms play a stabilization role via electrostatic and cationinteractions with nearby (aromatic)‐carbocyclic rings from both the ligand and from the reaction with unsaturated substrates. Since stabilizing K⋯H bonds are witnessed in the activation of this class of molecules, we aim to unveil the role of these metals in the activation of the smaller and less polarizable H2molecule, together with a comprehensive characterization of the reaction mechanism. In this work, the activation of H2utilizing a NON‐xanthene‐Al dimer, [K{Al(NON)}]2( D ) and monomeric, [Al(NON)]−(M ) complexes are studied using density functional theory and high‐level coupled‐cluster theory to reveal the potential role of K+atoms during the activation of this gas. Furthermore, we aim to reveal whetherD is more reactive thanM (or vice versa), or if complicity between the two monomer units exits within theD complex toward the activation of H2. The results suggest that activation energies using the dimeric and monomeric complexes were found to be very close (around 33 kcal mol−1). However, a partition of activation energies unveiled that the nature of the energy barriers for the monomeric and dimeric complexes are inherently different. The former is dominated by a more substantial distortion of the reactants (and increased interaction energies between them). Interestingly, during the oxidative addition, the distortion of the Al complex is minimal, while H2distorts the most, usually over 0.77. Overall, it is found here that electrostatic and induction energies between the complexes and H2are the main stabilizing components up to the respective transition states. The results suggest that the K+atoms act as stabilizers of the dimeric structure, and their cooperative role on the reaction mechanism may be negligible, acting as mere spectators in the activation of H2. Cooperation between the two monomers in D is lacking, and therefore the subsequent activation of H2is wholly disengaged. -
Abstract Keggin‐type polyaluminum cations belong to a unique class of compounds with their large positive charge, hydroxo bridges, and divergent isomerization/oligomerization. Previous reports indicated that oligomerization of this species can only occur through one isomer (δ), but herein we report the isolation of largest Keggin‐type cluster that occurs through self‐condensation of four ϵ‐isomers ϵ‐GeAl128+to form [Ge4O16Al48(OH)108(H2O)24]20+cluster (
Ge4Al48 ). The cluster was crystallized and structurally characterized by single‐crystal X‐ray diffraction (SCXRD) and the elemental composition was confirmed by ICP‐MS and SEM‐EDS. Additional dynamic light scattering experiments confirms the presence of theGe4Al48 in thermally aged solutions. DFT calculations reveal that a single atom Ge substitution in tetrahedral site of ϵ‐isomer is the key for the formation ofGe4Al48 because it activates deprotonation at key surface sites that control the self‐condensation process.