Abstract:The title compound, N,N,N′,N′‐tetramethylethylenediammonium diaqua(arsenate)(hydrogen arsenate)dizinc(II), (C6H18N2)0.5[Zn2(AsO4)(HAsO4)(H2O)2], is a new zincoarsenate obtained by hydrothermal synthesis. The structure consists of infinite two‐dimensional anionic layers alternating with planes containing centrosymmetric organic diprotonated template N,N,N′,N′‐tetramethylethylenediammonium cations, [H3NC6H12NH3]2+. The latter are interconnected to the framework through hydrogen bonds.
Eight new open-framework zinc arsenates, encompassing the entire hierarchy of open-framework structures, have been prepared hydrothermally. The structures include zero-dimensional, one-dimensional chains, two-dimensional layers, and three-dimensional structures formed through the transformation of the molecular zinc arsenates. The structure of [C6N4H21][Zn(HAsO4)2(H2AsO4)], I, is composed of ZnO4 and H2AsO4 units connected through the vertices forming four-membered rings with HAsO4 units hanging from the Zn center. The four-membered rings are connected through the corners forming the one-dimensional chain structures in [C4N2H12][Zn(HAsO4)2] x H2O, II, and [C5N2H14][Zn(HAsO4)2] x H2O, III. ZnO4 and AsO4 units form a fully four-connected two-dimensional structure in [C4N2H12][Zn(AsO4)]2, IV. One-dimensional zigzag ladders are connected through HAsO4 units forming two-dimensional layers in [C4N2H12]1.5[Zn2(AsO4)(HAsO4)2] x H2O, V, while the similar building units form a layer with hanging HAsO4 units in the layered arsenate [C6N4H21]6[Zn12(HAsO4)21], VI. Hanging HAsO4 units are also observed in the polymorphic structures of [C6N3H20][Zn2(AsO4)(HAsO4)2] x 2H2O, VII and VIII. Formation of zero-dimensional monomer, I, a fully four-connected layer, IV, and the polymorphic structures, VII and VIII, are important and noteworthy. The transformation reactions of I indicate that the monomer is reactive and gives rise to structures of higher dimensionalities, indicating a possible Aufbau-type building-up process in these structures.
Eight new open-framework zinc arsenates, encompassing the entire hierarchy of open-framework structures, have been prepared hydrothermally. The structures include zero-dimensional, one-dimensional chains, two-dimensional layers, and three-dimensional structures formed through the transformation of the molecular zinc arsenates. The structure of [C6N4H21][Zn(HAsO4)2(H2AsO4)], I, is composed of ZnO4 and H2AsO4 units connected through the vertices forming four-membered rings with HAsO4 units hanging from the Zn center. The four-membered rings are connected through the corners forming the one-dimensional chain structures in [C4N2H12][Zn(HAsO4)2] x H2O, II, and [C5N2H14][Zn(HAsO4)2] x H2O, III. ZnO4 and AsO4 units form a fully four-connected two-dimensional structure in [C4N2H12][Zn(AsO4)]2, IV. One-dimensional zigzag ladders are connected through HAsO4 units forming two-dimensional layers in [C4N2H12]1.5[Zn2(AsO4)(HAsO4)2] x H2O, V, while the similar building units form a layer with hanging HAsO4 units in the layered arsenate [C6N4H21]6[Zn12(HAsO4)21], VI. Hanging HAsO4 units are also observed in the polymorphic structures of [C6N3H20][Zn2(AsO4)(HAsO4)2] x 2H2O, VII and VIII. Formation of zero-dimensional monomer, I, a fully four-connected layer, IV, and the polymorphic structures, VII and VIII, are important and noteworthy. The transformation reactions of I indicate that the monomer is reactive and gives rise to structures of higher dimensionalities, indicating a possible Aufbau-type building-up process in these structures.
A three-dimensional iron arsenate [4,4'-bpyH2]3[Fe9(H2O)6F3(HAsO4)12(AsO4)2].2H2O, 1, has been synthesized using 4,4'-bipyridine as the templating agent under hydrothermal conditions. The structure is formed by FeO6, FeO3F3 octahedral units connected with HAsO4 and AsO4 units, forming one- and two-dimensional units in which the one-dimensional units act as a pillar. The presence of face-shared Fe-dimer units in the one-dimensional unit is noteworthy. Detailed magnetic studies indicate two possible magnetic interactions: antiferromagnetic interactions within the layer and a weak ferromagnetic polarization between the layers at very low temperatures through the Fe-dimer units.
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