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

ABSTRACT An anionic vanadium alumanyl complex is prepared by a reaction of neutral vanadocene and an alumanyl anion. Single‐crystal XRD revealed a significantly contracted V–Al bond relative to that of the neutral congener. Theoretical calculations using IBO and QTAIM analysis attributed this contraction to enhanced multiple‐bonding character based on the d‐p π‐backdonation from V to Al. Magnetic data confirms the S = 1/2 spin state of this anion, with EPR spectroscopy displaying relatively strong coupling between the V‐centered unpaired electron and the 27 Al nucleus. Furthermore, V K ‐edge XANES and XPS data revealed the oxidation states of the V and Al centers, highlighting the reduced nature of both metal centers. Reactivity studies revealed the dissociation of the anionic alumanyl ligand from the V center even in the presence of the multiple V─Al bond character, in stark contrast to the reactivity of the neutral analogue, as supported by a DFT‐based mechanistic study.