Control of open-framework structures through template⋯template interactions? Syntheses and structures of C2H7N4O⋅ZnCl(HPO4) and (C2H7N4O)2⋅Zn3(H2O)(HPO3)4

The syntheses and structures of C₂H₇N₄O⋅ZnCl(HPO₄) and (C₂H₇N₄O)₂⋅Zn₃(H₂O)(HPO₃)₄ are reported. Both phases arose in solution mediated reactions by way of the controlled, in situ, preparation of the cationic [C₂H₇N₄O]⁺ guanylurea template by the slow hydrolysis of the neutral 2-cyanoguanidine starting material. C₂H₇N₄O⋅ZnCl(HPO₄) contains anionic [ZnCl(HPO₄)]⁻ 6³-topology polyhedral layers built up from vertex-sharing ZnO₃Cl and HPO₄ polyhedra. (C₂H₇N₄O)₂⋅Zn₃(H₂O)(HPO₃)₄ is also layered and contains ZnO₄, ZnO₃(H₂O) and HPO₃ polyhedra sharing vertices by way of ZnOP bonds. In both structures, the guanylurea template participates in numerous template-to-framework and also template-to-template hydrogen bonds. Strikingly, the arrangement of template-to-template H bonds is different in the two structures, and also different to that seen earlier in C₂H₇N₄O⋅ZnPO₄. Crystal data: C₂H₇N₄O⋅ZnCl(HPO₄),Mr=299.91, monoclinic, Cc (No. 9), a=4.8823(2) Å, b=25.4781(11) Å, c=8.0335(4) Å,β=105.496(1)°, V=962.98(7) Å³; Z=4. (C₂H₇N₄O)₂⋅Zn₃(H₂O)(HPO₃)₄, Mr=740.27, triclinic,  (No. 2), a=9.0022(5) Å, b=9.5211(5) Å, c=13.4933(7) Å, α=94.986(1)°,β=94.111(1)°, γ=99.051(1)°, V=1133.51(1) Å³; Z=2.