Biomedical subjects

Ana María Atria

Publications and source records attributed to Ana María Atria.

5 recordsLinked to original sources

PubMed2006

Three oxo complexes with a tetranuclear [Cu(4)(mu(2)-Cl)(6)(mu(4)-O)] unit.

The three title compounds, namely 4-phenyl-1H-imidazolium hexa-mu(2)-chloro-chloro-mu(4)-oxo-tris(4-phenyl-1H-imidazole-kappaN(1))tetracopper(II) monohydrate, (C(9)H(9)N(2))[Cu(4)Cl(7)O(C(9)H(8)N(2))(3)]xH(2)O, hexa-mu(2)-chloro-mu(4)-oxo-tetrakis(pyridine N-oxide-kappaO)tetracopper(II), [Cu(4)Cl(6)O(C(5)H(5)NO)(4)], and hexa-mu(2)-chloro-tetrakis(2-methyl-1H-imidazole-kappaN(1))-mu(4)-oxo-tetracopper(II) methanol trisolvate, [Cu(4)Cl(6)O(C(4)H(6)N(2))(4)]x3CH(4)O, exhibit the same Cu(4)OCl(6) framework, where the O atom at the centre of an almost regular tetrahedron bridges four copper cations at the corners. This group is in turn surrounded by a Cl(6) octahedron, leading to a rather globular species. This special arrangement of the Cu(II) cations results in a diversity of magnetic behaviours.

Cations, Divalent↗

PubMed2006

Two oxo complexes with tetranuclear [Fe(4)(mu(3)-O)(2)](8+) and trinuclear [Fe(3)(mu(3)-O)](7+) units.

Two new oxo complexes, namely hexa-mu(2)-acetato-acetatoaquabis(di-3-pyridylamine)di-mu(3)-oxo-tetrairon(III) chloride monohydrate ethanol 1.25-solvate, [Fe(4)(C(2)H(3)O(2))(7)O(2)(C(10)H(9)N(3))(2)(H(2)O)]Clx1.25C(2)H(6)OxH(2)O, (I), containing a tetranuclear [Fe(4)(mu(3)-O)(2)](8+) unit, and 2-methylimidazolium hexa-mu(2)-acetato-acetatodiaqua-mu(3)-oxo-triiron(III) chloride dihydrate, (C(4)H(7)N(2))[Fe(3)(C(2)H(3)O(2))(7)O(H(2)O)(2)]Clx2H(2)O, (II), with a trinuclear [Fe(3)(mu(3)-O)](7+) unit, are presented. Both structures are formed by two well differentiated entities, viz. a compact isolated cluster composed of Fe(III) ions coordinated to O(2-) and CH(3)CO(2)(-) anions, and an external group formed by a central Cl(-) ion surrounded by different solvent groups to which the anion is bound through hydrogen bonding. In the case of (I), charge balance cannot be achieved within the groups, so the structure is macroscopically ionic; in the case of (II), in contrast, each group is locally neutral owing to the internal compensation of charges. The trinuclear complex crystallizes with the metal cluster, chloride anion and 2-methylimidazolium cation bisected by a crystallographic mirror plane.

Ferric Compounds↗

PubMed2003

Three yttrium crotonate complexes with diimines.

The synthesis and crystal structures of three new yttrium crotonate (crot) compounds, associated with three different nitrogenous bases, namely 1,10-phenanthroline (phen), 4-methyl-1,10-phenanthroline (mphen) and 2,2'-bipyridylamine (bpa), are presented. All three compounds organize as centrosymmetric dimers, to give tetra-micro-crotonato-bis[crotonato(1,10-phenanthroline)yttrium(III)] dihydrate, [Y(2)(C(4)H(5)O(2))(6)(C(12)H(8)N(2))(2)].2H(2)O or [Y(crot)(3)(phen)](2).2H(2)O, (I), tetra-micro-crotonato-bis[crotonato(4-methyl-1,10-phenanthroline)yttrium(III)] dihydrate, [Y(2)(C(4)H(5)O(2))(6)(C(13)H(10)N(2))(2)].2H(2)O or [Y(crot)(3)(mphen)](2).2H(2)O, (II), and tetra-micro-crotonato-bis[diaqua(crotonato)yttrium(III)] 2,2'-bipyridylamine tetrasolvate, [Y(2)(C(4)H(5)O(2))(6)(H(2)O)(4)].4C(10)H(9)N(3) or [Y(crot)(3)(aq)(2)](2).4(bpa), (III). Complexes (I) and (II) are isomorphous, with the bases acting as chelating ligands. In complex (III), the coordination sphere is built up of carboxylate and aqua ligands, with the non-coordinated diimine acting as included solvent.

Journal Article↗

PubMed2003

Two isomorphous imidazole (Him) complexes: [MCl(2)(Him)(2)(H(2)O)(2)] (M = Co and Ni).

The structures of aquadichlorobis(1H-imidazole)cobalt(II), [CoCl(2)(Him)(2)(H(2)O)(2)] (Him is 1H-imidazole, C(3)H(4)N(2)), (I), and aquadichlorobis(1H-imidazole)nickel(II), [NiCl(2)(Him)(2)(H(2)O)(2)], (II), are isomorphous and consist of monomers with inversion symmetry. The three monodentate ligands (imidazole, chlorine and aqua), together with their symmetry equivalents, define almost perfect octahedra. Hydrogen-bonding interactions via the imidazole and aqua H atoms lead to a three-dimensional network.

Journal Article↗

PubMed1997

Magnetic Interactions in the Copper Complex (L-Aspartato)(1,10-phenanthroline)copper(II) Hydrate. An Exchange-Coupled Extended System with Two Dissimilar Copper Ions.

We report EPR measurements in single-crystal samples at the microwave frequencies 9.8 and 34.3 GHz and magnetic susceptibility measurements in polycrystalline samples for the ternary complex of copper with aspartic acid and phenanthroline, (L-aspartato)(1,10-phenanthroline)copper(II) hydrate. The crystal lattice of this compound is composed of two dissimilar copper ions identified as Cu(A) and Cu(B), which are in two types of copper chains called A and B, respectively, running parallel to the b crystal axis. The copper ions in the A chains are connected by the aspartic acid molecule, and those in the B chains by a chemical path that involves a carboxylate bridge and a hydrogen bond. Both chains are held together by a complex network of hydrogen bonds and by hydrophobic interactions between aromatic amines. Magnetic susceptibility data indicate a Curie-Weiss behavior in the studied temperature range (2-300 K). The EPR spectra at 9.8 GHz display a single exchange collapsed resonance for any magnetic field orientation, in the so-called strong exchange regime. Those at 34.3 GHz are within the so-called weak exchange regime and display two resonances which belong to each type of copper ion chain. The decoupling of the spectra at 34.3 GHz using a theory based on Anderson's model for the case of two weakly exchange coupled spins S = (1)/(2) allows one to obtain the angular variation of the squares of the g-factor and the peak-to-peak line width of each resonance. This model also allows one to evaluate the exchange parameter |J(AB)/k| = 2.7(6) mK associated with the chemical path connecting dissimilar copper ions. The line width data obtained for each component of the spectra at 34.3 GHz are analyzed in terms of a model based on Kubo and Tomita's theory, to obtain the exchange parameters |J(A)/k| = 0.77(2) K and |J(B)/k| = 1.44(2) K associated with the chemical paths connecting the similar copper ions of types A and B, respectively.

Journal Article↗