Hydrothermal Syntheses and Single-Crystal Structures of Some Novel Guanidinium−Zinc−Phosphates

The mild-condition hydrothermal syntheses and single-crystal structures of three new guanidinium zinc phosphates are reported. CN3H6·Zn2(HPO4)2H2PO4 and (CN3H6)2·Zn(HPO4)2 are built up from three-dimensional Zn/P/O frameworks encapsulating guanidinium cations in 12-ring channel systems. The latter material has the lowest nodal-framework-atom density per unit volume of any open-framework phase characterized so far. (CN3H6)6·Zn2(OH)(PO4)3·H2O is a one-dimensional phase with respect to Zn/P/O connectivity and has a unique triply bridged tetrahedral chain connectivity for simple phosphates. Crystal data: CN3H6·Zn2(HPO4)2H2PO4, Mr = 478.78, monoclinic, space group P21 (No. 4), a = 5.1318(4) Å, b = 7.8411(7) Å, c = 16.510(1) Å, β = 90.110(7)°, V = 664.36(8) Å3, Z = 2, R = 2.43%, Rw = 2.67% [2608 observed reflections with I > 3σ(I)]. (CN3H6)2·Zn(HPO4)2, Mr = 377.50, orthorhombic, space group Pna21 (No. 33), a = 10.447(2) Å, b = 12.349(2) Å, c = 10.225(2) Å, V = 1319.2(5) Å3, Z = 4, R = 3.26%, Rw = 3.32% [2252 observed reflections with I > 3σ(I)]. (CN3H6)6·Zn2(OH)(PO4)3·H2O, Mr = 811.17, trigonal, space group R3̄ (No. 148), a = 20.016(7) Å, c = 13.955(6) Å, V = 4842(4) Å3, Z = 6, R = 5.31%, Rw = 5.52% [630 observed reflections with I > 3σ(I)].