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

Abstract

Hydrothermal treatment of CuCl 2·2H 2O, MoO 3, and 3,4′-dipyridylketone (3,4′-dpk) in 1:1:2 mole ratio afforded the new mixed metal oxide phases [Cu 2(MoO 4) 2(3,4′-dpk)(H 2O)] ( 1) or [Cu 4(3,4′-dpk) 4(Mo 8O 26)] ( 2), depending on the pH of the initial reaction mixture. Compound 1 possesses unique one-dimensional (1-D) [Cu 2(MoO 4) 2(H 2O)] n ribbons constructed from the linkage of {Cu II 4O 6} tetrameric units through isolated [MoO 4] 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 (6 28) 4(6 6) topology formed from the bracketing of discrete [ β–Mo 8O 26] 4– anions by four [ Cu I ( 3 , 4 ′ ‐ dpk ) ] n n + chains. The variable temperature magnetic susceptibility behavior of 1 was fit to a linear tetramer model, with g=2.03(3), J 1=25.8(7) cm –1 and J 2=−46(1) cm –1. Antiferromagnetic inter-tetramer interactions ( zJ′=−0.21(3) cm –1) were also evident. Crystallographic data: 1 monoclinic, P2 1/ c, a=10.3911(11) Å, b=6.9502(6) Å, c=22.958(2) Å, β=100.658(7)°, V=1629.5(3) Å 3, R 1=0.1256, and w R 2=0.2038; 2 triclinic, P 1 ¯ , 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) Å 3, R 1=0.0428, and w R 2=0.0630.