Equilibria in aqueous solution between Be(II) and iminodiacetic, N-methyliminodiacetic, N-ethyliminodiacetic and N-propyliminodiacetic acids

Electrospray Ionisation Mass Spectrometric (ESI MS) Screening and Characterisation of Beryllium Complexes with Potentially Encapsulating Aminopolycarboxylate and Related Ligands

“…Importantly, the speciation information provided by the ESI mass spectra of the Be 2+ /IDA system is in good agreement with potentiometric speciation data which have shown the [L –2H BeOH] – species to be the most prominent species when employing beryllium perchlorate as the source of Be 2+ , . Contrary to the perchlorate ion ClO 4 – , the sulfate group SO 4 2– has been observed elsewhere to bind strongly to the beryllium cation . Other ions detected in the negative ion mode at lower intensities include [BeL –3H ] – and [Be(L –H )(L –2H )] – at m/z 139 and 272 respectively.…”

“…Although no X‐ray structure for the beryllium complex with the IDA ligand has yet been reported, it has rigorously been shown employing potentiometric data that the IDA ligand is able to break up the cyclic beryllium trimer [Be 3 (OH) 3 ] 3+ by partially encapsulating the Be 2+ cation via tridentate coordination from two acetates and the amine group . It is apparent that the unavailability of donor atoms for complete tetrahedral coordination to beryllium (as observed in the NTP ligand) results in a partially encapsulated beryllium centre and the concomitant incorporation of a second ligand.…”

“…[24,25] Contrary to the perchlorate ion ClO 4 -, the sulfate group SO 4 2has been observed elsewhere to bind strongly to the beryllium cation. [26][27][28] Other ions detected in the negative ion mode at lower intensities include [BeL -3H ]and [Be(L -H )(L -2H )]at m/z 139 and 272 respectively. These species were only observed at higher capillary exit voltages (> 120 V).…”

“…In contrast, positive ion mass spectra of beryllium sulfate and iminodiacetic acid were less informative, revealing only a prominent signal corresponding to the sodiated free ligand [L+Na] + at m/z 156 as shown in Figure 2 Although no X-ray structure for the beryllium complex with the IDA ligand has yet been reported, it has rigorously been shown employing potentiometric data that the IDA ligand is able to break up the cyclic beryllium trimer [Be 3 (OH) 3 ] 3+ by partially encapsulating the Be 2+ cation via tridentate coordination from two acetates and the amine group. [28] It is apparent that the unavailability of donor atoms for complete tetrahedral coordination to beryllium (as observed in the NTP ligand) results in Figure 2. ESI mass spectra of BeSO 4 and iminodiacetic acid (L) in methanol/ water solution at capillary exit 60 V (a) positive ion mode (b) negative ion mode.…”