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Ricardo Baggio

Publications and source records attributed to Ricardo Baggio.

51 records · Page 3Linked to original sources
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↗
PubMed2003

Structure and magnetic properties of layered high-spin Co(II)(l-threonine)2(H2O)2.

We report the structure and the magnetic properties of a cobalt(II) compound with the amino acid l-threonine, Co(C(4)H(8)NO(3))(2)(H(2)O)(2). It crystallizes in the orthorhombic chiral space group C222(1), with a = 5.843(5) A, b = 10.120(10) A, c = 22.36(3) A, and Z = 4. The Co(II) ion is in a deformed octahedral environment on a 2-fold symmetry axis parallel to the crystallographic axis b. It is bonded to two threonine molecules in a bidentate fashion, via one oxygen from the carboxylate end and the alpha-amino nitrogen. A water molecule occupies the third independent site. The Co(II) ions are arranged in layers with intralayer and interlayer distances of 5.84 and 11.18 A, respectively. Magnetic measurements data reflect the molecular character of a compound with weak exchange interactions. EPR measurements in polycrystalline and single-crystal samples indicate a distorted axial symmetry around the Co(II) ion, as expected from the structural results. Eigenvalues and eigenvectors of the g tensor are determined. The measured principal g values (5.81, 4.56, and 2.23) reflect a high-spin Co(II) ion, as suggested by the type of ligands and the molecular symmetry. From the incomplete collapse of the hyperfine structure we estimate 0.25 < |J| < 1.2 cm(-1) between neighboring Co(II) ions within a layer, transmitted through H-bonds. A higher limit |J'| < 0.07 cm(-1) is estimated for the exchange interactions between Co(II) ions in neighboring layers. From a global fit of a spin Hamiltonian with spin (3)/(2) to magnetization and EPR data we obtain a zero field splitting delta approximately 231 cm(-1) between the two lowest doublet states. The results are discussed in terms of the molecular and electronic structure of the compound.

Cobalt↗
PubMed2003

[2,6-Bis(1H-benzimidazol-2-yl-kappaN3)pyridine-kappaN](dimethylformamide-kappaO)(thiosulfato-kappa2O,S)nickel(II) monohydrate.

The structure of the title compound, [Ni(ths)(bbip)(dmf)].H(2)O [ths is thiosulfate, S(2)O(3); bbip is 2,6-bis(1H-benzimidazol-2-yl)pyridine, C(21)H(13)N(5); and dmf is dimethylformamide, C(3)H(7)NO], is monomeric, with the nickel ion octahedrally surrounded by an N,N',N"-tridentate bbip molecule, an S,O-bidentate ths molecule and an O-monodentate dmf molecule. The H atoms of the hydration water molecule and the amino groups of bbip are involved in hydrogen bonding and determine a spatial organization of broad layers parallel to (001), which are connected by weak interactions.

Journal Article↗
PubMed2003

Bis[2,6-bis(1H-benzimidazol-2-yl-kappaN(3))pyridinato-kappaN]zinc(II).

The structure of [Zn(C(19)H(12)N(5))(2)], which is monomeric and consists of neutral Zn(bbip-H)(2) entities [bbip-H is the anionic form of bis(benzimidazolyl)pyridine, formed by the loss of one H atom], has been solved from a racemic twin. The Zn atom lies at a site with imposed 222 symmetry and the bbip-H ligand has imposed twofold symmetry. The imidazolyl H atom is disordered over two symmetry-related positions, thus raising the molecular symmetry as required by the space group. The angle between the planes of the two coordinated bbip-H ligands is 84.6 (3) degrees, so defining a distorted octahedral environment around the metal atom.

Journal Article↗
PubMed2003

Two hydrates of 2,6-bis(1H-benzimidazol-2-yl)pyridine.

The structures of the mono- and sesquihydrates of 2,6-bis(1H-benzimidazol-2-yl)pyridine (bbip) are reported. Phase (I), C(19)H(13)N(5).H(2)O, has one water and one bbip molecule in the asymmetric unit, while phase (II), C(19)H(13)N(5).1.5H(2)O, has three water molecules and two bbip molecules in the asymmetric unit. The compounds exhibit very similar molecular geometries but different packing organizations, which result from intricate hydrogen-bonding schemes.

Journal Article↗
PubMed2003

Polymeric hexaaquahexakis(mu3-2,2'-oxydiacetato)trizinc(II)digadolinium(III) dodecahydrate.

A polymeric heterometallic compound, ([Gd(2)Zn(3)(C(4)H(4)O(5))(6)(H(2)O)(6)].12H(2)O)(n), comprising zinc(II) and gadolinium(III) cations bridged by carboxylate groups from oxydiacetate ligands, is presented. The Gd(III) cations lie at sites with crystallographic 32 symmetry and display a tricapped trigonal-prism arrangement, which is defined by six carboxyl and three ether O atoms. The Zn(II) cations lie at sites with imposed 2/m symmetry and are octahedrally coordinated by four carboxyl O atoms and two apical water ligands, which form strong intramolecular hydrogen bonds. Comparison is made with the previously reported isostructural homologous copper-gadolinium complex.

Journal Article↗
PubMed2003

Two new dimeric cadmium(II) and zinc(II) sulfate complexes with 2,4,6-tris(2-pyridyl)-1,3,5-triazine and 2,2:6',2"-terpyridine.

The structures of two new sulfate complexes are reported, namely di-mu-sulfato-kappa(3)O,O':O"-bis(aqua[2,4,6-tris(2-pyridyl)-1,3,5-triazine-kappa(3)N(1),N(2),N(6)]cadmium(II)) tetrahydrate, [Cd(2)(SO(4))(2)(C(16)H(12)N(6))(2)(H(2)O)(2)].4H(2)O, and di-mu-sulfato-kappa(2)O:O'-bis[(2,2':6',2"-terpyridine-kappa(3)N(1),N(1'),N(1"))zinc(II)] dihydrate, [Cd(2)(SO(4))(2)(C(15)H(11)N(3))(2)].2H(2)O, the former being the first report of a Cd(tpt) complex [tpt is 2,4,6-tris(2-pyridyl)-1,3,5-triazine]. Both compounds crystallize in the space group P-1 and form centrosymmetric dimeric structures. In the cadmium complex, the metal center is heptacoordinated in the form of a pentagonal bipyramid, while in the zinc complex, the metal ion is in a fivefold environment, the coordination geometry being intermediate between square pyramidal and trigonal bipyramidal. Packing of the dimers leads to the formation of planar structures strongly linked by hydrogen bonding.

Journal Article↗
PubMed2002

A new polymeric phase of zinc(II) oxydiacetate.

A new polymeric phase of zinc(II) oxydiacetate, catena-poly[[[diaquazinc(II)]-mu-oxydiacetato] hydrate], [[Zn(C(4)H(4)O(5))(H(2)O)(2)].H(2)O](n), isomorphous with the Co homologue [Hatfield, Helms, Rohrs, Singh, Wasson & Weller (1987). Proc. Indian Acad. Sci. Chem. Sci. 98, 23-31], is reported. It presents a chain-like structure, generated by ZnO(6) cores which are bridged by carboxylate groups in an anti-anti conformation along the unique crystallographic b axis. The chains are held together through hydrogen-bonding interactions with the three water molecules.

Journal Article↗
PubMed2002

Carboxylate-bridged copper(II)-lanthanide(III) complexes [(Cu(3)Ln(2)(oda)(6)(H(2)O)(6)).12H(2)O](n)(Ln = Dy, Ho, Er, Y; oda = oxydiacetate).

The hydrothermal reaction of Ln(2)O(3) (Ln = Dy and Ho), Cu(OAc)(2).2H(2)O, and oxydiacetic acid in the approximate mole ratio of 1:3:8 resulted in the formation of two new members of the isostructural series of polymers formulated as [(Cu(3)Ln(2)(oda)(6)(H(2)O)(6)).12H(2)O](n), crystallizing in the hexagonal crystal system, space group P6/mcc (No. 192). Temperature-dependent magnetic susceptibilities and EPR spectra are reported for the heterometallic compounds Cu-Dy 1, Cu-Ho 2, Cu-Er 3, and Cu-Y 4. The results are discussed in terms of the structure of the compounds, the electronic properties of the lanthanide ions, and the exchange interactions between the magnetic ions.

Journal Article↗
PubMed2002

Bis(mu-acetato-kappa3O,O':O')bis[bis(acetato-kappa2O,O')diaquadysprosium(III)] tetrahydrate.

The title compound, [Dy(2)(C(2)H(3)O(2))(6)(H(2)O)(4)].4H(2)O, crystallizes in the form of dimeric units related by an inversion centre. Each cation is nine-coordinate, binding to two water molecules and three acetate groups, two of which are bidentate and the third tridentate. This last acetate group acts as a bridge between neighbouring metal atoms, leading to an intradimer Dy...Dy separation of 4.170 (1) A.

Journal Article↗
PubMed2002

Heterocyclization of 3-deoxy-D-erythro-hexos-2-ulose-1,2-bis(thiosemicarbazone). Crystal structure of the major diastereomer.

Both thiosemicarbazone groups of the derivative 1 of 3-deoxy-D-erythro-hexos-2-ulose underwent, on acetylation, a heterocyclization process to give (5R,5'R)-2,2'-diacetamido-4,4'-di-N-acetyl-5'-(1-deoxy-2,3,4-tri-O-acetyl-D-erythritol-1-yl)-5,5'-bis(1,3,4-thiadiazoline) (2) as a major product. The X-ray diffraction data of a single crystal of 2 indicated the R,R configuration for the stereocenters of the thiadiazoline rings (C-5 and C-5'). In the solid state, 2 adopts a sickle conformation (by clockwise rotation of the C-2-C-3 axis of the sugar chain) which has a S//O 1,3-parallel interaction. In solution, as determined by (1)H NMR spectroscopy which included NOE experiments, a similar sickle conformation was observed. From the reaction mixture of acetylation of 1 was isolated the bis(thiadiazoline) 3 as a by-product. The configuration of the C-5 and C-5' stereocenters of 3 were respectively assigned as S,R by comparison of the physical and spectroscopic data of this compound with those of 2.

Carbohydrate Conformation↗
PubMed2002

Bis(1,10-phenanthroline)(thiosulfato)manganese(II) methanol solvate and catena-poly[[diaqua(2,9-dimethyl-1,10-phenanthroline)manganese(II)]-mu-thiosulfato].

The structure of bis(1,10-phenanthroline-kappa(2)N,N')(thiosulfato-kappa(2)O:S)manganese(II) methanol solvate, [Mn(S(2)O(3))(C(12)H(8)N(2))(2)].CH(3)OH, is made up of Mn(2+) centers coordinated to two bidentate phenanthroline (phen) groups and an S,O-chelating thiosulfate anion, forming monomeric entities. The structure of catena-poly[[diaqua(2,9-dimethyl-1,10-phenanthroline-kappa(2)N,N')manganese(II)]-mu-thiosulfato-kappa(2)O:S], [Mn(S(2)O(3))(C(14)H(12)N(2))(H(2)O)(2)](n), is polymeric, consisting of Mn(dmph)(H(2)O)(2) units (dmph is 2,9-dimethyl-1,10-phenanthroline) linked by thiosulfate anions acting in an S,O-chelating manner.

Journal Article↗
PubMed2002

Two nickel complexes stabilized by nitrate counter-ions.

Two new nickel nitrates, diaquabis(3,4,7,8-tetramethyl-1,10-phenanthroline-kappa2N,N')nickel(II) dinitrate methanol solvate, [Ni(C(16)H(16)N(2))(2)(H(2)O)(2)](NO(3))(2) x CH(4)O, (I), and triaqua[2,4,6-tris(2-pyridyl)-1,3,5-triazine-kappa3N1,N2,N6]nickel(II) dinitrate trihydrate, [Ni(C(18)H(12)N(6))(H(2)O)(3)](NO(3))(2) x 3H(2)O, (II), are reported. In both structures, the cation is octahedrally coordinated, to two bidentate 3,4,7,8-tetramethyl-1,10-phenanthroline (tmp) and two water molecules in (I), and to one tridentate 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tpt) and three water molecules in (II). Both structures are stabilized by extensive hydrogen-bonding interactions.

Journal Article↗