Organically Templated Zirconium Fluorides: Hydrothermal Syntheses, Structural Relationships, and Thermal Behavior of (C_2H_10N_2)Zr_2F_10·H_2O and (C_4H_12N_2)ZrF_6·H_2o

摘要

The organically templated Zr(IV) fluorides, (C_2H_10N_2) Zr_2F_10·H_2O (AU2-6) and (C_4H_12N_2)ZrF_6·H_2O (AU1-6) have been prepared from the reaction of ZrO_2 with HF and ethylenediamine or piperazine under mild hydrothermal conditions. These compounds were characterized by single-crystal X-ray diffraction, DSC, TGA, and elemental analysis. AU2-6 consists of dodecahedral ZrF_8 units that share three edges with neighboring dodecahedra to form _(infinity~2)[Zr_2F_10]~(2-) sheets that are separated by diprotonated ethylenediamine cations. AU1-6 contains edge-sharing ZrF_8 dodecahedra that form _(infinity~1)[ZrF_6]~(2-) chains that further hydrogen bond with diprotonated piperazinium cations and water molecules. Application of dimensional reduction theory demonstrates that _(infinity~1)[ZrF_6]~(2-) chains can be derived from the _(infinity~2)[ZrF_10]~(2-) parent structure through the addition of one equivalent of fluoride. Thermal analyses indicate that the water molecules in AU2-6 are more tightly bound than those in AU1-6 as endotherms corrsponding to water loss occur at 226 and 117 deg C in AU2-6 and AU1-6, respectively. Crystallographic data: AU2-6, monolinic, space group P2_1, a = 6.164(1), b = 15.612(3), c = 11.227(2) A, #beta# = 95.31(3) deg, Z = 4, MoK#alpha#, #lambda#·0.71073, R(F) = 2.94% for 155 parameters with 3294 reflections with I > 2#sigma#(I); AU1-6, monoclinic, space group C2/m, a = 12.190(5), b = 12.732(6), c = 6.356(2) A, #beta# = 107.64(3) deg, Z = 4, MoK#alpha#, #lambda# = 0.71073, R(F) = 1.68% for 77 parameters with 869 reflections with I > 2#sigma#(I).