Abstract

The speciation of beryllium chloride solutions has been investigated using electrospray ionization mass spectrometry in both positive and negative ion modes. The majority of observed species were mixed beryllium-chlorido-oxido-hydroxido species, with the degree of hydration of the observed ions depending on the number of chloride ions. The observed species contain between 1 and 6 Be ions. The interactions of BeCl2 with a selection of crown ether ligands and cryptand[2.2.2] were also investigated using ESI MS. These ligands have low affinity for Be2+, instead the observed ions are dominated by species formed from adventitious Na+ or K+ ions. The crown ether 12-crown-4 showed the most complex spectra, as a result of greater interactions with Be2+, as evidenced by observed ions such as [BeX(12-crown-4)]+ (X = Cl or OH). The interactions of crown ethers with beryllium ions (as well as coordinated Cl- or OH- ancillary ligands) were investigated using Density Functional Theory [B3LYP/6-311++G(dp)], where it was shown that the species [BeX(crown ether)]+ (X = Cl or OH) are considerably more stable than [Be(crown ether)]2+ species, with 12-crown-4 forming the most stable complex. The combination of ESI MS and DFT investigations indicates that full encapsulation of the Be2+ by crown ethers is unfavorable, and coordination with an accompanying hydroxide or chloride is preferred.

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