Synthesis and characterization of alkali-metal tin(II) phosphates: Na10Sn31(HPO4)6(P2O7)6(PO4)12 and K2SnP2O7

Two new alkali-metal tin(II) phosphates – Na10Sn31(HPO4)6(P2O7)6(PO4)12 (1) and K2SnP2O7 (2) – were synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. Na10Sn31(HPO4)6(P2O7)6(PO4)12 crystallized in the noncentrosymmetric space group P-62c (No. 190) with a = 9.6445(1) Å, b = 9.6445(1) Å, c = 34.059(6) Å, V = 2743.6(7) Å3 and Z = 1. K2SnP2O7 crystallized in the monoclinic space group P21/n with a = 9.856(3) Å, b = 6.7244(1) Å, c = 12.225(3) Å, β = 108.240(5)°, V = 769. 5(3) Å3 and Z = 4. Both structures exhibit a novel open-framework structure. The crystal structure of 1 contains SnO3 and SnO4 polyhedra sharing corners with [HPO4]2−, [PO4]3− and [P2O7]4− groups, which form tunnels of six rings filled with Na+ cations and parallel to the c-axis, which are connected via O–Sn–O bridges to form a three-dimensional open framework. The crystal structure of 2 contains SnO4 seesaw polyhedra sharing corners with diphosphate groups to form a three-dimensional [SnP2O7]2− framework that exhibits a tunnel structure of 10- and 12-membered rings expanding along [011] and [100] with four arrays of K+ cations located in channels of the framework.

Graphical abstractTwo alkali-metal tin(II) phosphates – Na10Sn31(HPO4)6(P2O7)6(PO4)12 (1) and K2SnP2O7 (2) – were synthesized by high-temperature solid-state reactions. Both structures comprise novel open-framework structures. The structure contains tunnels of six-membered rings, which are connected via O–Sn–O bridges to form a three-dimensional open framework filled with Na+ cations and parallel to the c-axis. The crystal structure of 2 features a three-dimensional [SnP2O7]2− framework that comprises the tunnel structure of 10- and 12-membered rings expanding along [011] and [100] with K+ cations located in channels of the framework.Figure optionsDownload full-size imageDownload as PowerPoint slide