Carlos Jorge da Cunha

Bis(2,2′-bipyridine)(1,2-diimino-9,10-anthraquinone)ruthenium(II): a complex containing an exceptionally strong π-accepting α-α′ diimine ligand I. Synthesis, crystal and electronic structures

Abstract The compound 1,2-diamino-9,10-anthraquinone (DAAQ) binds to ruthenium bis-(2,2′-bipyridine) forming a complex containing the oxidized 1,2-diimino-9,10-anthraquinone (DIAQ). The complex was crystallized as [Ru(bpy)2DIAQ](1,3-benzenedisulfonate)·6.5H2O. Crystal data: triclinic, space group P1−, a = 10.095(2) A , b = 12.035(2) A , c = 17.652(4) A , α = 97.50(3)°, β = 92.54(3)°, γ = 91.65(3)° , Z = 2 . The metal is bound to the diimine site of the DIAQ ligand. There is an extensive n backbonding interaction between the DIAQ ligand and the metal as inferred from theoretical calculations, electrochemical and spectroscopic data. The DIAQ is the best a accepting neutral α-α′ diimine ligand known to date.

O programa de gerenciamento dos resíduos laboratoriais do Depto de Química da UFPR

The Laboratory Waste Management Program of the Chemistry Department of UFPR started on 1997 and was developed to meet the requirements of co-processing in cement kiln and those of the respective regulation. The in-lab procedures for waste collection and treatment were devised taking into account their cost, simplicity and wide range of application to the various types of residues generated. The program works with a five step annual journey : 1) Waste collection and treatment, 2) Bulk Storage, 3) Licensing (for transportation and co-processing), 4) Transportation and 5) Co-processing.

ISOTHIOCYANATE COPPER(II) TETRAAZA-IMINOOXIME MACROCYCLIC COMPLEX: AN EXAMPLE OF LINKAGE ISOMERISM. PART I — SYNTHESIS, INFRARED SPECTROSCOPY AND CRYSTAL STRUCTURE

Abstract The isothiocyanate complex [Cu(DOHPN)(NCS)] (DOHPN = 3, 3′-trimethylenedinitrilobis-(2-butanone oxime)) has been prepared and characterized by infrared spectroscopy and X-ray crystallography as the isomer of the thiocyanate complex whose crystal structure is found in the literature. The formula unit of the title compound, is [Cu(DOHPN)(NCS)]2[Cu(DOHPN)-(H2O)](ClO4) corresponding to C35H59ClCu3N14O11S2- The crystal is triclinic, space group P-1, Z = 2, and has the following lattice constants: a = 7.460(l) A, b = 11.541(2)A, c = 29.149(6)A, a = 97.44(3)°, β = 91.32(3)°, γ = 96.68(3)°. In each of the three complexes which compose the formula unit, the copper(II) lies in a square pyramidal environment made of an axial ligand and four nitrogen atoms of the tetraaza ligand. The stronger the interaction between copper(II) and the axial ligand, the more the DOHPN bends resulting in a “butterfly-like” geometry. Formation of the thiocyanate isomer is kineti-cally favored over the thermodynamically more sta...

Synthesis of enaminones with stationary stereochemistry

Cinco enaminonas 4a-e, derivadas da reacao do ânion da 2,4,4-trimetil-2-oxazolina com acetato de etila, benzoato de etila, ciclohexanoato de etila, hexanoato de etila e p-metil benzoato de etila, respectivamente, foram preparadas e caracterizadas por RMN1H, RMN13C, FTIR e EM. As enaminonas 4a e 4b tambem foram analisadas pela tecnica de difracao de raios-X. A enaminona 4a cristalizou-se no sistema monoclinico P2(1)/n, grupo espacial com a = 9.1450(20) A, b = 10.5150(20) A, c = 9.5670(20) A, b = 106.21(30)°, Z = 4. A enaminona 4b cristalizou-se no sistema monoclinico P2(1)/c, grupo espacial com a = 16.0520(30) A, b= 26.0460(50) A, c = 12.3520 (20) A, b= 111.900(30)°, Z = 4. Todas as cinco enaminonas possuem uma extensa delocalizacao de eletrons p e a mesma configuracao para a ligacao dupla, a qual e fixada por ponte de hidrogenio intramolecular entre os grupamentos NH e C=O.

Mössbauer, vibrational and electronic spectroscopy of trinuclear μ-oxo iron(III) acetate clusters with pyridine and derivatives as ligands

Abstract In this study we have investigated eight complexes of the general composition [Fe 3 O(OOCCH 3 ) 6 (L) 3 ]NO 3 , where L is a heterocyclic ligand, viz. a 4-substituted pyridine. The Mossbauer spectra of the complexes showed isomer shifts and quadrupole splittings that are characteristic of iron(III) high-spin complexes. The Mossbauer quadrupolar doublets showed asymmetries that are attributed principally to the Goldanskii-Karyagin effect. A correlation is proposed between the Mossbauer parameters, and between the energy of the charge transfer band spectra, and the p K a values of the N-heterocyclic ligands.

(Imidazole)(3,3′-trimethylenedinitrilo bis (2-butanone oximate)) copper(II) perchlorate: Synthesis and crystal structure of a five-coordinate copper-protein model complex

The synthesis and crystal structure of the novel pentacoordinated complex [Cu(DOHPN)(IMI-DAZOLE)] (ClO4), (DOHPN=(3,3′-trimethylenedinitrilo bis 2-butanone oxime) are reported. The X-ray crystal structure (space groupP21/n, a=11.349(2) Å,b=14.241(3) Å,c= 12.635(3) Å; α=90°, β=100.21 (3)°, γ=90°) shows that the copper(II) ion occupies a distorted square-pyramidal geometry with the imidazole ligand occupying the axial position. The copper(II)-(N)imidazole distance is 2.125(3) Å and the copper(II)-tetraaza plane distance is 0.385/Å. The tetraaza ligand DOHPN adopts a “butterfly-like” geometry with a dihedral angle of 149.69°. The title complex is the first structurally characterized compound of the series [Cu(DOHPN)(axial ligand)]n+ where the axial ligand is a neutral N-heterocycle with known biological relevance. A comparison of the structural parameters with those observed when the axial ligand is H2O or NCS− (N-bonded) gives the following series with increasing metal-ligand interaction: H2O>IMIDAZOLE>NCS− (N-bonded).

Photomultiplier nonlinear response in time-domain laser-induced luminescence spectroscopy

A new procedure to find the limiting range of the photomultiplier linear response of a low-cost, digital oscilloscope-based time-resolved laser-induced luminescence spectrometer (TRLS), is presented. A systematic investigation on the instrument response function with different signal input terminations, and the relationship between the luminescence intensity reaching the photomultiplier and the measured decay time are described. These investigations establish that setting the maximum intensity of the luminescence signal below 0.3V guarantees, for signal input terminations equal or higher than 99.7 ohm, a linear photomultiplier response.