Four Novel Metal Diphosphonate Compounds Based on 2-(1-Triazole)-1-Hydroxyl-1,1′-Ethylidenediphosphonic Acid: Syntheses, Topological Structures, and Magnetic Properties

Hydrothermal reactions of Mn(H), Cu(II), Co(II), and Ni(II) salts with 2-(1-triazole)-1-hydroxyl-1,1'-ethylidenediphosphonic acid (tahedpH(4)) lead to four novel metal phosphonates, namely, Mn-2(tahedp)(H2O)(2) (1), Cu-2(tahedp)(H2O) (2), Co(tahedpH(2)) (3) and Ni-2(tahedpH(2))(2) center dot (NH2CH2CH2NH2) (4). In compound 1, dimeric units {Mn1(2)O(2)} are linked together by the O3-P1-O1 groups forming an inorganic chain. The adjacent chains are further connected by {Mn2O(4)N} pentahedra to form an undulating inorganic layer. The inorganic layers are bridged by the triazole groups resulting in a three-dimensional framework structure. In the opinion of the topology, the structure of 1 can be described as an unprecedented trinodal (4.6(6).8(3))(2)(4(2).6(2).8(2)) (5.6(2))(2) topological network. Compound 2 shows a pillared layered structure in which the (CU1(2)O(2)) dimers are linked together by the O3-P1-O1 groups forming a double chain. The double chains and the {Cu2-O5-P2-O4-}(2) eight-membered rings are further linked through the coordination of 02 and 06 atoms into a layer. The neighboring layers are connected together by the triazole rings, resulting in a pillared layered structure. Topological analysis of compound 2 reveals that it is a unique 3, 4, and 5-connected net with (4(2).6)(2)(4(2).8(4))(4(3).6.8(6))(2) topology. Compound 3 exhibits a layer structure made up of Co-2(tahedpH(2))(2) dimer units. Compound 4 exhibits a layer architecture that built from {NiO5N} octahedra interconnected by phosphonate groups and triazole rings. Magnetic measurements reveal that antiferromagnetic interactions are mediated between magnetic centers in all four compounds.