Maria Teresa do Prado Gambardella

Anhydrous copper(II) hexanoate from cuprous and cupric oxides. The crystal and molecular structure of Cu2(O2CC5H11)4

Abstract The synthesis and spectroscopic, magnetic and structural characterization of a complex of copper(II) with hexanoic acid, Cu2(O2CC5H11)4 are described. The same complex is formed by synthesis using either CuO or Cu2O. The compound exhibits a typical dinuclear paddle-wheel type structure, consisting of two copper(II) ions in square-pyramidal geometry bridged by four carboxylate anions in the xy plane. The IR spectrum shows that the ΔνCOO for this complex appears at 171 cm−1 which corresponds to a bridging bidentade mode of coordination of carboxylate-to-metal. Elemental analysis, EPR spectra and TG analysis were also performed. The magnetic susceptibility measurement confirms the antiferromagnetic nature of the copper–carboxylate coupling which is in agreement with the X-ray crystallography results.

Chemical and electrochemical characterization of a novel nanocomposite formed from V2O5 and poly(N-propane sulfonic acid aniline), a self-doped polyaniline

Synthesis and characterization of new nanocomposites of V 2 O 5 and a sulfonated, alkylated polyaniline derivative [poly(N-propane sulfonic acid aniline), PSPAN] are described. Two types of PSPAN-V 2 O 5 nanocomposites have been produced, one by reaction of vanadium triisopropoxide solutions with N-propane sulfonic acid aniline and one by addition of H 2 O 2 to these same solutions. Nanocomposites are characterized using thermal gravimetric analysis, differencial scanning calorimetry (DSC), cyclic voltammetry, chronopotentiometry, and impedance spectroscopy. The increase of the 001 reflection spacing, X-ray diffraction results show that the polymer is intercalated into the V 2 O 5 interlayer region, consistent with the nanocomposite nature of the material. The DSC and infrared data suggest that water coordinated to vanadium sites exposed to the interlayer region is lost during formation of the nanocomposite. SEMs show that, in contrast to the relatively flat and featureless V 2 O 5 .1.6H 2 O thin films, the nanocomposites are highly textured and have quite small feature sizes. Electrochemical results show that some of the nanocomposites have larger specific capacity (307 Ah/kg) and faster reduction kinetics than V 2 O 5 .16.H 2 O and similar cyclability. The relevance of these results to general approaches to the production of nanocomposites for Li secondary battery cathodes is discussed.

Diphosphine complexes of nickel: analogies in molecular structures and variety in crystalline arrangement

Abstract This work comprised the preparation of six complexes of Ni(II) and their study by spectroscopy and X-ray diffraction. These complexes are: [Ni(dppe)Cl2]CH2Cl2 (I), [Ni(dppen)Cl2] (II), [Ni(dppm)Br2]CH2Cl2 (III), [Ni(dppe)(NCS)2] (IV), [Ni(dppen)I2] (V), [Ni(dppp)Cl2]CH2Cl2 (VI), where dppe=1,2-bis(diphenylphosphine)ethane, dppen=cis-1,2-bis(diphenylphosphine)ethene, dppm=bis(diphenylphosphine)methane, dppp=1,3-bis(diphenylphosphine)propane. The structures of complexes III–VI are unknown in the literature. Although the molecular structures of the six complexes present many similarities, their crystalline arrangements vary considerably. This is a feature not presented hitherto in previous work involving complexes of this type. In addition, a systematic spectroscopic study was undertaken on all six complexes.

Nitrosyl ruthenium complexes with general formula [RuCl3(NO)(PP)] (PP = {PPh2(CH2)nPPh2}, n = 1–3 and {PPh2-CHPPh2}). X-ray structure of [RuCl3(NO){PPh2(CH2)3PPh2}]

Abstract Ruthenium(II) complexes with general formula [RuCl3(NO)(PP)] were obtained in the solid state, where PP = PPh2(CH2)nPPh2 (n = 1) and PPh2-Ch = CH-PPh2. The 31P NMR spectra of these compounds measured in CH2Cl2 showed only singlets, consistent with a fac configuration containing two equivalent phosphorus atoms. However the X-ray diffraction data show that the [RuCl3(NO){PPh2(CH2)3PPh2}] complex crystallizes in a mer configuration, where one of the phosphorus atoms is trans to the NO group, in a slightly distorted octahedral geometry.

Isolamento e atividades biológicas de produtos naturais das esponjas monanchora arbuscula, aplysina sp. petromica ciocalyptoides e topsentia ophiraphidites, da ascídia didemnum ligulum e do octocoral carijoa riisei

The investigation of extracts from six species of marine invertebrates yielded one new and several known natural products. Isoptilocaulin from the sponge Monanchora aff. arbuscula displayed antimicrobial activity at 1.3 mg/mL against an oxacillin-resistant strain of Staphylococcus aureus. Five inactive known dibromotyrosine derivatives, 2 6, were isolated from a new species of marine sponge, Aplysina sp. The sponges Petromica ciocalyptoides and Topsentia ophiraphidites yielded the known halistanol sulfate A (7) as an inhibitor of the antileishmanial target adenosine phosphoribosyl transferase. The ascidian Didemnum ligulum yielded asterubin (10) and the new N,N-dimethyl-O-methylethanolamine (11). The octocoral Carijoa riisei yielded the known 18-acetoxypregna-1,4,20-trien-3-one (12), which displayed cytotoxic activity against the cancer cell lines SF295, MDA-MB435, HCT8 and HL60.The investigation of extracts from six species of marine invertebrates yielded one new and several known natural products. Isoptilocaulin from the sponge Monanchora aff. arbuscula displayed antimicrobial activity at 1.3 mg/mL against an oxacillin-resistant strain of Staphylococcus aureus. Five inactive known dibromotyrosine derivatives, 2 6, were isolated from a new species of marine sponge, Aplysina sp. The sponges Petromica ciocalyptoides and Topsentia ophiraphidites yielded the known halistanol sulfate A (7) as an inhibitor of the antileishmanial target adenosine phosphoribosyl transferase. The ascidian Didemnum ligulum yielded asterubin (10) and the new N,N-dimethyl-O-methylethanolamine (11). The octocoral Carijoa riisei yielded the known 18-acetoxypregna-1,4,20-trien-3-one (12), which displayed cytotoxic activity against the cancer cell lines SF295, MDA-MB435, HCT8 and HL60.

Synthesis and solid-state structural characterization of bis (thiocyanatemercury)tetracarbonyliron

Abstract The bis (thiocyanatemercury)tetracarbonyliron, [Fe(CO)4(HgSCN)2], was prepared from [Fe(CO) 5] and Hg(SCN)2, and studied by IR spectroscopy and X-ray diffraction. The compound crystallizes in the tetragonal space group I4,1/a. The unit cell, with dimensions of a = 13.778(3), c = 13.234(3) A, V = 2512.3(9) A3, contains four molecules. The iron atom is octahedrally coordinated by four carbonyl groups and two mercury atoms in cis positions. The coordination of the mercury atoms is distorted square-planar, since, besides mercury-iron and mercury—sulphur bonds, there are also mercury—mercury and mercury-nitrogen interactions. The FeHg distance is 2.506(5)A and the HgFeHg angle is 78.0(1)°.

Synthesis and characterization of the mer-[RuCl3(NO)(dppb)] isomer. X-ray structures of fac-[RuCl3(NO)(dppm)], cis-[RuCl2(dppm)2] and mer-[RuCl3(NO)(dppb)] [dppm=1,2-Bis(diphenylphosphino)methane and dppb=1,4-Bis(diphenylphosphino)butane]

Abstract The fac-[RuCl3(NO)(dppm)] (1) and cis-[RuCl2(dppm)2] (2) complexes were obtained with co-crystallization in the solid state from the reaction of RuCl3(NO) with the diphosphine in dichloromethane. mer-[RuCl3(NO)(dppb)] (3) was obtained from [RuCl3(dppb)(H2O)] by bubbling NO for 30 min in the same solvent. The crystal and molecular structures of these three compounds have been determined from X-ray studies.

New Heptacoordinated Organotin(IV) Complexes Derivatives of 2,6-diacetylpyridinebis(2-furanoylhydrazone), H2dapf, and 2,6-diacetylpyridinebis(2-thenoylhydrazone), H2dapt: Crystal and Molecular Structure of [Me2Sn(Hdapt]Br.H2O

The reaction of the ligands H2dapf and H2dapt, with R4-mSnXm (m = 2, 3; R = Me, Ph and X = Cl, Br) led to the formation of eight new heptacoordinated organotin(IV) complexes, which were studied by microanalysis, IR, NMR and Mossbauer spectroscopy to investigate their structural properties. The methyl derivative [Me2Sn(Hdapt)]Br.H2O was also studied by single crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P21/c, with a = 21.920(3), b = 7.4470(5), c = 16.805(2) A, b = 110.18(1)o, Z = 4. The structure determination revealed a monocationic complex of Sn(IV) in a distorted bipyramidal geometry [Me2Sn(Hdapf)]+, with Br- as counter ion and one molecule of water helping the crystal packing. Mossbauer parameters of the complex [Me2Sn(Hdapf)]2[Me2SnCl4] have evidenced two Sn(IV) sites, as observed in the crystal structure determination. Also a correlation between Mossbauer and X-ray data based on the point-charge model is discussed.

Synthesis and structural studies of bis(1,10-phenanthrolinethiocyanatemercury) tetracarbonyliron

Abstract The bis(1,10-phenanthrolinethiocyanatemercury)tetracarbonyliron was prepared from bis(thiocyanatemercury)tetracarbonyliron and 1,10-phenanthroline and crystallized from hot acetone solution as [Fe(CO) 4 (HgSCN) 2 (phen) 2 ]·C 3 H 6 O, which was subjected to a full IR and X-ray crystallographic characterization. The iron atom is octahedrally coordinated by four carbonyl groups and two mercury atoms in cis positions. The coordination geometry of the mercury atoms is a distorted square-based pyramid since each one is coordinated to one iron, one sulphur, one mercury and two nitrogen atoms. The FeHg distances are 2.549(3) and 2.564(3) A, and the HgFeHg angle is 78.01(9)°.

Structural properties of trans-chloro(4-acetylpyridine) (1,4,8,11-tetraazacyclotetradecane)ruthenium(II)_ tetrafluoroborate, trans-[RuCl(cyclam)(4-acpy)] (BF4), by X-ray diffraction and NMR spectroscopy☆

The X-ray structural analysis of trans-[RuCl(cyclam)(4-acpy)](BF4) (cyclam  1,4,8,11-tetraazacyclotetradecane; 4-acpy  4-acetylpyridine) showed that the crystals are monoclinic, space group l2/a, with a = 19.216(2), b = 11.345(1), c = 20.336(2) A, β = 96.30(1)°, V = 4407(1) A3 and Z = 8. The complex adopts the trans geometry, with the macrocycle in the chair conformation. RuN (cyclam) interatomic distances range from 2.085(6) to 2.118(7) A, and their values are smaller than those in other Ru(II) amine complexes and are closer to Ru(III)N (amine) interatomic distances. The Ru(II)N(4-acpy) interatomic distance is 2.057(7) A and is longer than expected when compared with pyrazine, bis(isonicotinamide) or 1-methylpyrazinium Ru(II) ammine complexes, and base on the 4-acpy back-bonding ability as deducted from reduction potentials and metal-to-ligand charge-transfer absorption bands. ClH(N4) and ClH(N8) interatomic distances are smaller than the sum of the van der Waals radii of H and Cl, indicating a bonding interaction. 13C and 1H NMR spectra in d6-dimethyl sulfoxide and d6-acetone showed the same geometry and conformation of the macrocycle in solution.