“…This technique is known to be used in combination with traditional solution chemistry techniques to investigate metal–ligand interactions. , Actinide species have been studied by ESI-MS since the early 1990s where the use of electrospray mass spectrometry was utilized for the analysis of various elements including U(VI), , Th(IV), − Am(III), ,− Np and Pu in different oxidation states. − The publications range from species identification to specific interest in the chemistry of the f-elements ,, through the investigation of competitive interactions . Additionally, a number of studies have included the use of ESI-MS to investigate the gas phase behavior of UO 2 + , UO 2 2+ , PuO 2 + and PuO 2 2+ ,,− ,− Pu(III), ,, Pu(IV) gas phase behavior , and Rios et al reported the gas phase reduction of PuO 2 2+ to Pu(V) and Pu(IV) followed by ESI-MS . The ESI-MS spectra in positive ionization mode of 1 after dissolution of some crystals in THF and 1/1000 dilution in CH 3 CN are reported in the Figures S5 and S6.…”