Multiple-Bonding and Lability: Study of an Anionic Vanadium Alumanyl

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry

Background:

• Vanadocene chemistry provides a platform for exploring metal-ligand bonding.
• Alumanyl anions are novel ligands with unique electronic properties.

Purpose of the Study:

• To synthesize and characterize a novel anionic vanadium alumanyl complex.
• To investigate the nature of the V-Al bond and its electronic structure.
• To compare the reactivity of the anionic complex with its neutral counterpart.

Main Methods:

• Synthesis of the anionic vanadium alumanyl complex.
• Single-crystal X-ray diffraction (XRD) for structural analysis.
• Theoretical calculations including Independent Gradient Model (IGM) and Quantum Theory of Atoms in Molecules (QTAIM) analyses.
• Magnetic susceptibility measurements and Electron Paramagnetic Resonance (EPR) spectroscopy.
• X-ray Absorption Near Edge Structure (XANES) and X-ray Photoelectron Spectroscopy (XPS).
• Density Functional Theory (DFT) for mechanistic studies.

Main Results:

• A significantly contracted V-Al bond was observed, indicating enhanced multiple bonding character attributed to V-to-Al d-p π-backdonation.
• The complex exhibits an S = 1/2 spin state, with strong coupling between the V-centered electron and the 27Al nucleus.
• V K-edge XANES and XPS data confirmed reduced oxidation states for both V and Al centers.
• Reactivity studies showed facile dissociation of the alumanyl ligand, contrasting with the neutral analogue despite the strong V-Al bond.

Conclusions:

• The anionic vanadium alumanyl complex features a strong, multiple V-Al bond stabilized by π-backdonation.
• Despite the strong bonding, the alumanyl ligand shows lability, offering unique reactivity pathways.
• This study advances the understanding of bonding in vanadium-aluminum compounds and their chemical behavior.