The reactions between aqueous solutions of M
4+ (M = Zr, Hf) and PO
3S
3- each result in the precipitation of awhite gel that can be dried to a powder. Elemental analysis results for the white polycrystalline product yield astoichiometry of H
2M(PO
3S)
2. These new compounds are characterized by thermal analysis (DSC, TG-MS),vibrational spectroscopy (FT-IR, FT-Raman),
31P MAS NMR spectroscopy, energy-dispersive spectroscopy (EDS),and powder X-ray diffraction (XRD). On the basis of the characterizations and the results of trialkylamineintercalation experiments, we conclude that the H
2M(PO
3S)
2 compounds have a layered structure that is likelysimilar to that of
![](/images/gifchars/alpha.gif)
-H
2Zr(PO
4)
2·H
2O. The interlayer spacing for both H
2M(PO
3S)
2 compounds, determined byXRD, is ~9.4 Å. Our characterization results suggest that the sulfur atom of each PO
3S
3- group is preferentiallypointed into the interlayer region of the compound and is protonated. Two of the many potentially interestingproperties of H
2Zr(PO
3S)
2, its ion-exchange capacity and selectivity, are investigated. H
2Zr(PO
3S)
2 is demonstratedto be an effective and recyclable ion-exchange material for both Zn
2+(aq) and Cd
2+(aq). Mass balance experimentsindicate that the removal of Cd
2+(aq) and Zn
2+(aq) ions by solid H
2Zr(PO
3S)
2 occurs by an ion-exchange process.Ion exchange results in the formation of the new compounds H
0.2Cd
0.9Zr(PO
3S)
2 and H
0.50Zn
0.75Zr(PO
3S)
2. Theextraction of metal ions is monitored by XRD, vibrational spectroscopy, and elemental analysis. H
2Zr(PO
3S)
2reversibly intercalates Zn
2+(aq) ions through three complete cycles of intercalation and deintercalation withoutany loss of ion-exchange capacity.