HYDROLYSIS OF BERYLLIUM(II) IN DMSO-H2O

The hydrolysis of beryllium(II) in the systems Be(II)-H2O and Be(II)-d imethyl sulfoxide:water (80:20, w:w) has been studied at 25 degrees C by Be-9 NMR and e.m.f. titrations in 0.5 mol dm(-3) NaClO4, using glas s and calomel electrodes. The beryllium concentration and the -log[H+] was varied in the ranges 1-20 x 10(-3) mol dm(-3) and 2.8-6.1 respect ively. The mathematical analysis of the curves Z, average number of OH . bound per Be(ll), as a funtion of -log[H+] indicates the presence of the species [Be2OH](3+), [Be-3(OH)(3)](3+), [Be-5(OH)(6)](4+), [Be-6( OH)(8)]4(+) and Be(OH)(2).-log beta(pq) values are: 3.20(1), 8.68(3), 18.31(5), 25.77(5) and 11.68(6) respectively in aqueous solution, wher eas in the mixed solvent dimethyl sulfoxide:water (80:20, w:w) the -lo g beta(pq) values are: 2.98(2), 9.28(3), 18.03(3), 25.16(4), 9.59(3) r espectively, and 5.25(3) for the complex [Be(OH)](+). It was concluded that, in aqueous solution, the main hydrolytic product is [Be-3(OH)(3 )](3+), whereas in the mixed solvent it was the monomeric species [Be( OH)](+) and Be(OH)(2), because the coordination of dimethyl sulfoxide to beryllium(ll) decreses the stability of polynuclear hydroxo-complex es.