Inorganic−Metalorganic Hybrids Based on Copper(II)-Monosubstituted Keggin Polyanions and Dinuclear Copper(II)−Oxalate Complexes. Synthesis, X-ray Structural Characterization, and Magnetic Properties

Abstract

Reaction of in situ generated copper(II)-monosubstituted Keggin polyoxometalates and copper(II)-bipyridine-oxalate complexes in the corresponding alkaline acetate buffer led to the formation of hybrid metal organic-inorganic compounds K(2)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(H(2)O)(2)(mu-ox)}(2)].14H(2)O (1), K(14)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}](2)[SiW(11)O(39)Cu(H(2)O)].55H(2)O (2), (NH(4))(4)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}].10H(2)O (3), and Rb(4)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}].10H(2)O (4). Their structures have been established by single-crystal X-ray diffraction. The main structural feature of these compounds is the presence of copper(II)-monosubstituted alpha-Keggin polyoxoanions as inorganic building blocks, on which the mu-oxalatodicopper metalorganic blocks are supported. Compound 1contains the discrete hybrid polyanion [{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(H(2)O)(2)(mu-ox)}(2)](2)(-), whereas the polymeric hybrid polyanion [{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}(2)](n)(4)(n)(-) gives a monodimensional character to compounds 2-4. Magnetic and EPR results are discussed with respect to the crystal structure of the compounds. DFT calculations on both the [Cu(2)(bpy)(2)(H(2)O)(4)(mu-ox)](2+) cationic complex and the metalorganic blocks have been performed in order to determine the optimized geometry and the magnetic coupling constants, respectively.

A novel Keggin-type tungstogermanate dimer bearing dinuclear copper-organic coordination ions: {H8[Cu(phen)(μ2-CH3COO)2Cu(phen)(H2O)]2[Ge2W23CuO80]}·24H2O

“…The room-temperature EPR spectrum displays an anisotropic broad resonance centers at approximately 3400 G with the effective g = 2.16, as expected for copper (II) systems [18,19]. Moreover, three less intense signals are observed at 1600, 2700 and 4000 G. This set of signals can be associated with a well-isolated triplet spin state showing a relatively small zero-field splitting, and, therefore, it may be originated from the Cu II dimer [14].…”

Synthesis, structures and electrochemical properties of four organic–inorganic hybrid polyoxometalates constructed from polyoxotungstate clusters and transition metal complexes

“…Recently, the emerging rate of POMs with novel structures reported is much faster than ever before [18]. The remarkable bidentate ligands, 2,2 0 -bpy and 4,4 0 -bpy, first seized our attention because (1) the linear rigid 4,4 0 -bpy ligand contains two terminal pyridyl groups in the opposite position, which has been explored in constructing extended structures [19][20][21][22]; (2) The chelating 2,2 0 -bpy ligand also presents a structural versatility [23][24][25]. Besides, aromatic N-containing ligands may provide recognition sites for p-p stacking interactions to form interesting supramolecular networks.…”

Two oxamido-bridged binuclear Cu–M complexes (M = CoII, CuII): synthesis, crystal structures and magnetic studies

“…Recently, many polynuclear complexes in which the metals have different geometries or oxidation states including 1D-3D supramolecular architectures have been designed and synthesized [15][16][17][18][19][20][21]. At the same time, the exchange coupling among paramagnetic centers typically leads to a ferromagnetic or antiferromagnetic behavior [22][23][24][25].…”