Two new phosphates, Sr2M(PO4)2(H2PO4) (M = VIII or FeIII), have been synthesised hydrothermally at 230°C and characterized by single-crystal X-ray diffraction and thermal analysis. Crystal data: Sr2V(PO4)2(H2PO4), monoclinic, space group C2/c, a = 11.078(3), b = 11.742(3), c = 8.951(3) Å, β = 125.35(2)°, Z = 4 and R = 0.0356; Sr2Fe(PO4)2(H2PO4), as above except a = 11.082(2), b = 11.737(2), c = 8.961(2) Å, β = 125.45(1)° and R = 0.0273. The two compounds are isostructural. The structure consists of ∞1[M(PO4)4/2(H 2PO4)2/2] units along the  direction, held together by hydrogen bonding and O-Sr-O bonds. The interaction between the structural unit and the interstitial species has been evaluated using the valence-matching principle to account for the presence of an interstitial H2O in the structure of the related compound Ca2V(PO4)(HPO4)2·H 2O. Dehydration of the compounds at 750 and 650°C yields Sr2V(PO4)(P2O7) and Sr2Fe(PO4)(P2O7), respectively.
|Number of pages||4|
|Journal||Journal of the Chemical Society - Dalton Transactions|
|State||Published - 1993|