title: Structures, magnetic and catalytic properties of three sandwich-type silicotungstates containing tetranuclear copper(II) clusters.
abstract: Three sandwich-type silicotungstates, formulated as [Cu4(H2O)2(SiW9O34)2] x 12 NH4 x 22 H2O (1), [Cu4(H2O)2(SiW9O34)2] x 12 NH4 x 11 H2O (2) and {[Cu(NH3)4]2[Cu(H2O)4][Cu4(H2O)2(SiW9O34)2]} 2[Cu(NH3)4(H2O)] x 2 NH4 x 6 H2O (3), were synthesized by microwave irradiation and hydrothermal reaction. Crystal structural analysis reveals that 1-3 possess the same dimeric polyoxoanions [Cu2SiW9O34(H2O)]2(12-) featuring tetranuclear copper(II) clusters. Magnetic studies indicate that the Cu4 clusters exhibit ferromagnetic coupling interactions. Investigation on their catalytic activity for the oxidation of ethylbenzene suggests that catalytic activity of 1-3 is closely related to the acidity of complexes and the existence of unsaturated coordination sites in the complex.
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surface and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Yu
authors.forename: Yu-Xiang
authors.initials: YX
authors.lastname: Long
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Ren
authors.forename: Xiang-Jian
authors.initials: XJ
authors.lastname: Kong
authors.forename: La-Sheng
authors.initials: LS
authors.lastname: Long
authors.forename: Rong-Bin
authors.initials: RB
authors.lastname: Huang
authors.forename: Lan-Sun
authors.initials: LS
authors.lastname: Zheng