Topologically novel copper molybdate phases based on 3,4′-dipyridylketone: Hydrothermal synthesis, structural characterization, and magnetic properties

Hydrothermal treatment of CuCl2·2H2O, MoO3, and 3,4′-dipyridylketone (3,4′-dpk) in 1:1:2 mole ratio afforded the new mixed metal oxide phases [Cu2(MoO4)2(3,4′-dpk)(H2O)] (1) or [Cu4(3,4′-dpk)4(Mo8O26)] (2), depending on the pH of the initial reaction mixture. Compound 1 possesses unique one-dimensional (1-D) [Cu2(MoO4)2(H2O)]n ribbons constructed from the linkage of {CuII4O6} tetrameric units through isolated [MoO4]2– tetrahedra. These ribbons in turn are connected into a two-dimensional (2–D) coordination polymer structure by tethering 3,4′-dpk ligands. Compound 2, containing monovalent copper ions, manifests an unprecedented “X-rail” 1-D extended structure with (628)4(66) topology formed from the bracketing of discrete [β–Mo8O26]4– anions by four image chains. The variable temperature magnetic susceptibility behavior of 1 was fit to a linear tetramer model, with g=2.03(3), J1=25.8(7) cm–1 and J2=−46(1) cm–1. Antiferromagnetic inter-tetramer interactions (zJ′=−0.21(3) cm–1) were also evident. Crystallographic data: 1 monoclinic, P21/c, a=10.3911(11) Å, b=6.9502(6) Å, c=22.958(2) Å, β=100.658(7)°, V=1629.5(3) Å3, R1=0.1256, and wR2=0.2038; 2 triclinic, image a=10.9000(3) Å, b=11.7912(4) Å, c=13.5584(4) Å, α=102.482(2)°, β=102.482(2)°, γ=117.481(2)°, V=1450.98(8) Å3, R1=0.0428, and wR2=0.0630.