HYDROLYSIS OF BERYLLIUM(II) IN DMSO : H2O

Abstract

The hydrolysis of beryllium(ll) in the systems Be(ll)-H20 and Be(ll)-dimethyl sulfoxide:water (80:20, w:w) has been studied at 25C by titrations in 0.5 mol dm' 3 NaCI0 4 , using glass and calomel electrodes. The beryllium concentration and the -logJH 4 ] was varied in the ranges 1-20X10" 3 mol dm" 3 and 2.8-6.1 respectively. The mathematical analysis of the curves Z, average number of OH' bound per Be(ll), as a funtion of -logtH 4 ] indicates the presence of the species [Be 2 OH] 3+ , [ 3 () 3 , [Be 5 (OH) 6 ] 4+ , [Be 6 (OH) 8 ] 4+ and Be(OH) 2 .-log w values are: 3.20(1), 8.68(3), 18.31(5), 25.77(5) and 11.68(6) respectively in aqueous solution, whereas in the mixed solvent dimethyl sulfoxide:water (80:20, w:w) the -log w values are: 2.98(2), 9.28(3), 18.03(3), 25.16(4), 9.59(3) respectively, 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 monomelic species [Be(OH)] + and Be(OH) 2 , because the coordination of dimethyl sulfoxide to beryllium(ll) decreses the stability of polynuclear hydroxo-complexes.