Crystal-to-crystal polymerisation of monosubstituted [PWOCu(HO)] Keggin-type anions.

The reaction between neutral bis(picolinate)copper(II) complexes and copper(II)-monosubstituted Keggin-type phosphotungstate anions formed leads to the formation of the hybrid [C(NH)][{PWOCu(HO)}{Cu(pic)}]·10HO compound (1, pic = picolinate) in the presence of structure-directing guanidinium cations. Single-crystal X-ray diffraction studies demonstrate that 1 contains dimeric {PWOCu(HO)}{Cu(pic)} molecular species constituted by two Keggin-type anions linked by one {Cu(pic)} octahedral complex through axial coordination to their terminal oxygen atoms. The extensive hydrogen-bonding network established by guanidium cations and Keggin clusters plays a key role in retaining the crystallinity of the system throughout dehydration to allow a single-crystal-to-single-crystal (SCSC) transformation into the anhydrous [C(NH)][{PWOCu}{Cu(pic)}] (2a) at 170 °C.

Rearrangement of a Krebs-type polyoxometalate upon coordination of N,O-bis(bidentate) ligands.

Selective coordination of 2,3-pyzdc to the Krebs-type [{Ni(H2O)3}2(WO2)2(SbW9O33)2](10-) anion promotes a skeletal rearrangement that results in the [(2,3-pyzdc)2{NaNi2(H2O)4Sb2W20O70}2](22-) (Ni4) hybrid dimer showing a novel dinickel containing a 20-tungsto-2-antimonate(III) framework stabilized by N,O-bis(bidentate) bridging ligands. The solution stability and magnetism of Ni4 is discussed.

Functionalization of Krebs-type polyoxometalates with N,O-chelating ligands: a systematic study.

The first organic derivatives of 3d-metal-disubstituted Krebs-type polyoxometalates have been synthesized under mild bench conditions via straightforward replacement of labile aqua ligands with N,O-chelating planar anions on either preformed or in situ-generated precursors. Nine hybrid clusters containing carboxylate derivatives of five- or six-membered aromatic N-heterocycles as antenna ligands have been obtained as pure crystalline phases and characterized by elemental and thermal analyses, infrared spectroscopy, and single-crystal X-ray diffraction. They all show the general formula [{M(II)L(H2O)}2(WO2)2(B-β-XW9O33)2](n-) and can be classified as follows: 1-SbM, where L = 1H-imidazole-4-carboxylate (imc), X = Sb(III), n = 12, and M(II) = Mn, Co, Ni, Zn; 1-TeM, where L = imc, X = Te(IV), n = 10, and M(II) = Mn, Co; 2-SbNi, where L = 1H-pyrazole-3-carboxylate (pzc), X = Sb(III), n = 12, and M(II) = Ni; and 3-SbM, where L = pyrazine-2-carboxylate (pyzc), X =Sb(III), n = 12, and M(II) = Co, Zn.

trans-Di-aqua-bis-(pyridazine-3-carboxyl-ato-κ(2) N (2),O)copper(II).

In the title compound, [Cu(C5H3N2O2)2(H2O)2], the Cu(II) ion, located on an inversion center, exhibits an octa-hedral coordination geometry. The equatorial plane is defined by two trans-related N,O-bidentate pyridazine-3-carboxyl-ate ligands and the axial positions are occupied by two water mol-ecules. In the crystal, mol-ecules are connected by O-H⋯O hydrogen bonds between the water mol-ecules and the noncoordinating carboxyl-ate O atoms, forming layers parallel to the bc plane.

Diaqua-bis-(1H-imidazole-4-carboxyl-ato-κ(2)N(3),O)cobalt(II).

The title compound, [Co(C(4)H(3)N(2)O(2))(2)(H(2)O)(2)], contains a Co(II) cation on a twofold rotation axis, exhibiting a distorted octa-hedral coordination geometry. The equatorial plane is formed by two N,O-bidentate 1H-imidazole-4-carboxyl-ate ligands and the axial positions are occupied by water mol-ecules. The crystal packing consists of a three-dimensional network stabilized by O-H⋯O and N-H⋯O hydrogen bonds, together with weak π-π inter-actions [centroid-centroid distance = 3.

Tetra-kis(μ(2)-ferrocene-carboxyl-ato-κO:O')bis-[(methanol-κO)copper(II)] methanol disolvate.

The complex mol-ecule of the title compound, [Cu(2)Fe(4)(C(5)H(5))(4)(C(6)H(4)O(2))(4)(CH(3)OH)(2)]·2CH(3)OH, lies about an inversion centre and contains two centrosymetrically related Cu(II) atoms bridged by four O:O'-bidentante ferrocene-carboxyl-ate anions, leading to a dimeric tetra-bridged unit with a paddle-wheel geometry. The Cu(II) atom has a distorted square-pyramidal coordination environment with four O atoms from four ferrocene-carboxyl-ate ligands in basal positions and an O atom from a methanol mol-ecule in an apical position. One of the two crystallographically independent ferrocenyl groups has a staggered conformation, while the other is eclipsed.