New High-Dimensional Networks Based on Polyoxometalate and Crown Ether Building Blocks

Three novel supramolecular assemblies constructed from polyoxometalate and crown ether building blocks,
[(DB18C6)Na(H2O)1.5]2Mo6O19·CH3CN, 1, and [{Na(DB18C6)(H2O)2}3(H2O)2]XMo12O40·6DMF·CH3CN (X = P, 2,
and As, 3; DB18C6 = dibenzo-18-crown-6; DMF = N,N-dimethylfomamide), have been synthesized and characterized
by elemental analyses, IR, UV−vis, EPR, TG, and single crystal X-ray diffraction. Compound 1 crystallizes in the
tetragonal space group P4/mbm with a = 16.9701(6) Å, c = 14.2676(4) Å, and Z = 2. Compound 2 crystallizes
in the hexagonal space group P63/m with a = 15.7435(17) Å, c = 30.042(7) Å, γ = 120°, and Z = 2. Compound
3 crystallizes in the hexagonal space group P63/m with a = 15.6882(5) Å, c = 29.9778(18) Å, γ = 120°, and Z
= 2. Compound 1 exhibits an unusual three-dimensional network with one-dimensional sandglasslike channels
based on the extensive weak forces between the oxygen atoms on the [Mo6O19]2- polyoxoanions and the CH2
groups of crown ether molecules. Compounds 2 and 3 are isostructural, and both contain a novel semiopen cagelike
trimeric cation [{Na(DB18C6)(H2O)2}3(H2O)2]3+. In their packing arrangement, an interesting 2-D “honeycomblike”
“host” network is formed, in which the [XMo12O40]3- (X = As and P) polyoxoanion “guests” resided.