Gas phase fragmentation provides structural insights into mixed-ligand polyoxovanadate alkoxides

The design of atomically precise clusters with targeted properties for non-aqueous redox flow batteries often requires tailoring the ligand shell, yielding distributions of mixed-ligand species. Mass spectrometry can probe the structures of individual components in such mixtures without prior separation. Here, we employ collision-energy-resolved collision-induced dissociation (CID) in both positive and negative modes to investigate polyoxovanadate-alkoxides (POV-alkoxides) with a Lindqvist core and ethoxy/ethoxyethyl (EtO/EOE) mixed-ligand shell. These POV-alkoxides have been described previously as promising candidates for flowable energy storage technologies. Cationic species are markedly less stable toward fragmentation than their anionic analogues. Low-energy fragmentation in positive mode reveals a bias toward EOE incorporation into ionic fragments, corroborating ligand segregation rather than a statistical distribution around the core. In contrast, anionic species require higher energies and display near-statistical ligand incorporation into fragment ions, obscuring segregation, and generate numerous fragments, complicating spectral interpretation. These findings establish charge- and composition-dependent fragmentation pathways, providing a framework for structural elucidation of POV-alkoxides with mixed ligand shells using CID.