
TY  - JOUR
A1  - Baldwin, WG 
A1  - Stranks, DR 
T1  - Beryllium-chrome-azurol-S complexes
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1968
VL  - 21
IS  - 3
SP  - 603
EP  - 615
KW  - 
UR  - https://doi.org/10.1071/CH9680603 
N2  - Complex formation between the aquated beryllium cation and the tetrabasic dyestuff chrome-azurol-S (H4CAS) has been studied by spectrophotometric, potentiometric, electrophoretic, and ion-exchange techniques. At least two complexes are shown to exist within the pH range 3-6. The major species is the anionic complex BeHCAS- for which log &#946;11, = 4.66 ± 0.08 at 25º and at ionic strength 0.lM (NaClO4) Coordination of beryllium is considered to occur at the quinonoid-,).   carboxylato site in the HCAS8- ligand. The stability constant for the dinuclear species Be2CASO is shown to be log &#946;21 = 15.8 ± 0.1 under the same medium conditions. The dinuclear complex interferes with spectrophotometric measurements at beryllium concentrations exceeding 2.5 x 10-4. The acidity constants of H4CAS were determined at 25º and at an ionic strength 0.IM (NaClO,) as pK2a = 2.25 ± 0.10,pK3a, = 4.88 ± 0.05, pK4, = 11.75 ± 0.05, whilst pK1a = -1.2 ± 0.4. 
ER  -

