“…Mass spectrometry, particularly ESI MS, has had long and illustrious history in inorganic structural analysis and related fields, although complex physical processes occurring within the ESI interface frequently require that the conclusions derived from such measurements be taken cum grano salis. For example, high-resolution measurements of ionic isotopic distributions allow the oxidation states to be determined at both single 43,44 and multi-metal level, 45 but the measurement outcomes can be affected by the redox processes in the ESI interface. Likewise, mass measurements afforded by high-resolution MS provide a unique opportunity to unequivocally identify a wide range of metallo-compounds, but can be complicated by the metastable nature of molecular ions giving rise to their dissociation in the gas-phase.…”