Andres Vega

Synthesis, structure and oxidation studies of a dinuclear copper(I)–copper(II) complex: [Cu2(bdpdz)2](ClO4)3

Abstract A dinuclear copper complex containing the ligand 3,6-bis(di-2-pyridylmethyl) pyridazine, bdpdz, [Cu2(bdpdz)2](ClO4)3, was prepared and its structure determined by X-ray analysis. The compound consists of a dinuclear mixed valence copper(I)–copper(II) entity with localised valences, co-ordinated to two bridging ligand molecules. The geometry around the copper(I) centre is distorted tetrahedral, while that of the copper(II) centre is tetragonally distorted octahedral. Oxidation studies reveal that the compound does not exhibit phenolase activity.

Iron–iron interaction through an ethanedithiolate ligand: a magnetic and theoretical study

Abstract The compound ([CpFe(dppe)]2[μ-SCH2CH2SS,S′])(PF6)2 ([1][PF6]2) has been synthesized and its magnetic properties have been investigated by susceptometer quantum interface device (SQUID) measurements in the temperature range 5–300 K. The d5–d5 12+ complex exhibits intramolecular antiferromagnetic behavior, with a magnetic coupling constant of −6.4 cm−1. Density functional theory (DFT) calculations on a model of 12+ (as well as on models of 1+ and 1) allow to determine its molecular structure and analyse its bonding and magnetic properties. The computed spin density exhibits significant localization on both the Fe and S centers. Replacing the heteroatoms of the bridging ligand by CH2 groups leads to a relocalization of the spin density on the metal atoms and favors ferromagnetic coupling.

Synthesis and characterization of polynuclear complexes of molybdenum carbonyl derivatives with pyridine-2-carbaldehyde azine (pa) and ferrocenylphosphines. Crystal structure of [Mo2(CO)6(μ-dppf)(μ-pa)] (dppf 1,1′-bis(diphenylphosphino)ferrocence)

Abstract Novel mono- and didentate ferrocenylphosphines containing complexes, [Mo 2 (CO) 6 (dfpp) 2 ( μ -pa)] (dfpp  diferrocenylphenylphosphine) and [Mo 2 (CO) 6 ( μ -dppf)( μ -pa)], have been isolated and characterized by infrared and electronic spectroscopy, and cyclic voltammetry. For the [Mo 2 (CO) 6 (μ-dppf)(μ-pa)] complex a single crystal X-ray structure analysis evidences its double bridge nature and the asymmetry of the bridging ligands due to steric constraints. In the visible region, the new compounds show strong solvatochromic bands and this effect has been evaluated by using the E MLCT ∗ parameter. The redox behaviour of the complexes involves molybdenum and ferrocene-based oxidations and pa-based reductions. The results are compared to the previously characterized analogous complexes based on the related ligands triphenylphosphine and 1,2- bis (diphenylphosphino)ethane.

The crystal and molecular structures of two bromo bis(N,N-dipropylthiocarbamoyl) sulfidocopper(I) complexes

The reaction of copper(I) bromide, CuBr, with the tetraalkylthiurammonosulfides R4tms (R = iPr, nPr) affords the copper(I) complexes iPr4tmsCuBr (I) (C14H28BrCuN2S2, orthorhombic, Pna21, Z = 4, a = 12.487(2), b = 12.699(2), c = 12.742(2) Å) and nPr4tmsCuBr (II) (C14H28BrCuN2S3, monoclinic, P21/n, Z = 4, a = 9.092(5), b = 23.408(11), c = 10.082(7) Å, β = 104.90(5)°), which exist in the solid as monomeric units featuring three-coordinate copper(I). The ligands are bidentate and coordination is completed by the bromine atoms. The configurations of the six-membered metal-ligand ring in (I) and (II) are more severely distorted than the previously reported structurally related complexes of ethyl series. The crystal structural studies are complemented and confirmed by IR and 1H-NMR spectroscopies, as well as room temperature, magnetic, solution conductivity, and molecular weight studies.

INFLUENCE OF HYDROGEN BRIDGES ON THE MAGNETIC PROPERTIES OF COPPER(II) BIS(TRIFLUOROACETATE) COMPLEXES

Unidades monometalicas de trifluoroacetato de cobre(II) con tres moleculas de agua coordinadas cristalizan en forma de cadenas lineales via puentes de hidrogeno, rodeadas por moleculas de dioxano de solvatacion. El complejo [Cu(H2O)3(OOCCF3) 2]·2(C4H8O2 ) (1) cristaliza en el sistema triclinico grupo espacial P1, con a = 6.067(1)A, b = 12.153(3)A, c = 15.057(3)A, a= 100.09(2), b= 99.15(2), g= 101.00(2) y Z = 2. El EPR de (1) muestra dos senales (g

Nonacarbonyl-μ2-hydrido-μ2-(N-methylcarboxamido)-C :O-(N-trimethylamine)triosmium(3 Os-Os)

In the title compound, nonacarbonyl-1κ 2 C,2κ 3 C,3κ 4 C--hydrido-1:2κ 2 H-μ-(N-methylcarboxamido)-1:2κ 2 O:C-(N-trimethylamine-1κN)triosmium(3 Os-Os), [Os 3 H-(C 2 H 4 NO)(C 3 H 9 N)(CO) 9 ] the MeHNCO ligand forms a μ 2 -C:O bridge between two metal centers, which are also linked by a μ-hydride ligand. These two groups are at opposite sides of the plane defined by the Os atoms. Bond lengths between Os atoms are 2.8149(8), 2.8777(8) and 2.9278 (8) A. The structure shows two metal centers which are heptacoordinated and one which is hexacoordinated.

EPR spectra of (L-aspartate)di(2-pyridyl)aminezinc(II) hydrate substitutionally copper(II) doped complex

The [(L-aspartate)di(2-pyridyl)aminezinc(II)]hydrate doped with traces of copper was prepared. Electron paramagnetic resonance spectra of the polycrystalline sample were recorded at room temperature by using the X-band of the EPR spectrometer. The observedg factors for the complex areg‖=2.258 andg⊥=2.066. TheA‖ value is 165.10−4 cm−1. The crystal and molecular structure of the complex are also reported. The complex crystallizes in the monoclinic system; space groupP21 witha=7.2053(11),b=10.447(2),c=10.812(2) Å, β=108.489(14)° andZ=2. The structure can be described in the crystal lattice as polymeric chains.

Reactivity of [trans-R2MoO(NNPhR′)(o-phen)] toward R′PhNNH2 and R′PhNNH3+Cl−, R=Me, Ph and R′=Me, Ph. X-ray structure of [trans-MeClMoO(NNPh2)(o-phen)]

Abstract The reactivities of [trans-R2MoO(NNPhR′)(o-phen)], R=R′=Me (1); R=Me, R′=Ph (2); R=Ph, R′=Me (3); R=R′=Ph (4), toward (i) neutral 1,1-disubstituted hydrazines, R′PhNNH2 and (ii) 1,1-disubstituted hydrazine hydrochlorides, R′PhNNH2·HCl, R′=Me, Ph, were studied in acetonitrile. In the first case, no condensation reaction of the free oxo group was observed under different experimental conditions. In the second case, using a 1:1 precursor/hydrazine hydrochloride molar ratio, the oxo group was also unreactive, instead one methyl or phenyl group bonded to molybdenum was displaced as methane or benzene and was subsequently substituted by one chloride ligand affording complexes formulated as [trans-RClMoO(NNPhR′)(o-phen)], R=R′=Me (5); R=Me, R′=Ph (6); R=Ph, R′=Me, (7)·MeCN; R=R′=Ph, (8)·MeCN. Finally, when a 1:2 precursor/hydrazine hydrochloride molar ratio was used, both methyl and phenyl groups were substituted affording complexes formulated as [trans-Cl2MoO(NNPhR′)(o-phen)], R′=Me (9), R=Ph (10). The new organometallic compounds were characterised by IR, UV–Vis and 1H NMR spectroscopy while the crystal and molecular structure of 6 was determined by X-ray diffraction analysis.