Monobasic strontium arsenite can be prepared by
heating a slurry of strontium hydroxide and adding
a solution of arsenious acid:
Sr(OH)2 + 2H3AsO3 ? Sr(H2PO3)2 + 2H2O
The pH needs to be about 9.5–10.0. Strontium arsenite
tetrahydrate, Sr(H2AsO3)2·4H2O, has a molecular
weight of 373.5234 g/mol and a CAS number of 10378-
48-0. It is a white powder that is slightly soluble in
H2O but insoluble in EtOH. It is soluble in dilute acids.
When heated, it loses two waters of hydration at 105°C
and the other two at 155°C. The crystal structure of
strontium dihydrogen phosphite, Sr(H2PO3)2, contains
eightfold-coordinated Sr ions connected by dihydrogenphosphite
anions so that a layer structure is formed.
