title: Rare sandwich-type polyoxomolybdates constructed from Di-/tetra-nuclear transition-metal clusters and trivacant keggin germanomolybdate fragments.
abstract: Two types of rare sandwich-type germanomolybdates [Na(12)(H(2)O)(36)][Cu(2)(beta-Y-GeMo(9)O(33))(2)].3H(2)O (1), [N(CH(3))(4)](4) [Na(6)(H(2)O)(24)][Cr(2)(beta-Y-GeMo(9)O(33))(2)].7H(2)O (2), and [Na(11)(H(2)O)(25)]H[M(4)(H(2)O)(2)(alpha-B-GeMo(9)O(34))(2)].6H(2)O (M = Ni(II) for 3, M = Mn(II) for 4 and M = Co(II) for 5) have been synthesized and characterized by elemental analyses, ICP spectra, IR spectroscopy, UV spectroscopy, thermogravimetry (TG) analyses (for 1-3), X-ray photoelectron spectroscopy (XPS) (for 1 and 3), X-ray powder diffraction (XRPD) (for 1 and 3) and single-crystal X-ray diffraction. To our knowledge, 1-5 represent the first sandwich-type germanomolybdates containing both {beta-Y-GeMo(9)O(33)}/{alpha-B-GeMo(9)O(34)} fragments and transition-metal clusters. Interestingly, 1 and 2 display the rare dinuclear transition-metal substituted sandwich-type structures with unusual trivacant {beta-Y-GeMo(9)O(33)} germanomolybdate units whereas 3-5 exhibit the first tetranuclear transition-metal substituted sandwich-type structures with familiar trivacant {alpha-B-GeMo(9)O(34)} germanomolybdate units. Surface photovoltage spectroscopy (SPS) and electric field induced surface photovoltage spectroscopy (EFISPS) measurements reveal that 1 and 3 bear the behavior of the n-type semiconductor. Magnetic measurements indicate 1 and 3 demonstrate antiferromagnetic exchange interactions and ferromagnetic exchange interactions, respectively.
authors.affiliation: Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, PR China.
authors.forename: Suzhi
authors.initials: S
authors.lastname: Li
authors.forename: Junwei
authors.initials: J
authors.lastname: Zhao
authors.forename: Pengtao
authors.initials: P
authors.lastname: Ma
authors.forename: Juan
authors.initials: J
authors.lastname: Du
authors.forename: Jingyang
authors.initials: J
authors.lastname: Niu
authors.forename: Jingping
authors.initials: J
authors.lastname: Wang