2. Release of a short-Iived“metaphosphate” group, which rapidly recovers the 4-connected orthophosphate structure:
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17-8
Complex Chemistry of Group VB Elements
The main aqueous chemistry of SbIII is in oxalato, tartrate, and similar hydroxyacid complexes.
The สมการ ion forms isolable saltsand has been shown to have the incomplete pentagonal-bipyramid structure (Fig. 17-3) with a lone pair at one axial position. The tartrate complexes of antimony(III) have been much studied, and have been used medicinally as "tartar emetic" for more than 300 years. The structure of the anion in this salt,สมการ 3 HA), is shown in Fig. 17-4.
Only for Bi is there a true cationic chemistry. Aqueous solutions contain well-defined hydrated cations, but there is no evidence for a simple aquo ion [Bi(H2O)n]3+. In neutral perchlorate solutions the main species is [Bi6O6]6+ or its hydrated form, [Bi(OH)12]6+, and at higher pH [BiO6(OH)3]3+is formed. The [Bi(OH)12]6+ species contains an octahedron of Bi 3+Ions with an OH- bridging each edge.
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Figure 17-3 Theสมการion projected on a plane approximately perpendicular to the basal plane of the pentagonal pyramid