Showing papers by "Mariana Mitewa published in 1992"
TL;DR: In this paper, seven new styryl dyes containing an aza-15-crown-5 moiety were synthesized and characterized by means of elemental analysis, m.p., UV, I R and 1H-NMR spectra.
21 citations
TL;DR: A new platinum complex with creatinine [C3H2 N2(O)(CH3)NH2] exhibiting paramagnetic properties was synthesized fully characterized by crystallographic, spectral magnetic measurements as mentioned in this paper.
11 citations
TL;DR: In this article, two extraction systems incorporating novel derivatives of benzothiazole are described for the determination of trace amounts of HgII and PdII by flame atomic absorption spectrometry (AAS).
Abstract: Two extraction systems incorporating novel derivatives of benzothiazole are described for the determination of trace amounts of HgII and PdII by flame atomic absorption spectrometry (AAS). The extraction ability of the systems was studied both in strongly acidic (3 mol dm–3 HCl) and slightly acidic (Ph 5) media. By using the equilibrium shift method the composition of the extracted complexes was determined. The experimental data obtained indicate that the composition of the complexes depends on the acidity of the reaction system. A procedure for the extraction, separation, preconcentration and flame AAS determination of HgII in Pb, Cu and Cd salts was developed, allowing 2 × 10–4% Hg to be determined.
7 citations
TL;DR: In this paper, the structure and coordination mode of the ligand were studied by means of EPR, IR, TG and DTA methods and the results showed that by varying the reaction conditions (acidity, metal-to-ligand ratio, presence of oxygen), different platinum and palladium complexes are obtained.
7 citations
TL;DR: In this paper, a fast reaction of 4-(2-p -dimethylaminophenyl ethynil)-6, 6-dimethyl-3-cyano-5,6-dihydro-2(1H)-pyridone (DHP) with the intermediate complex of platinum(III), PtCl 2− 5, appearing in the photoreduction of PtCl2− 6 in methanol was investigated.
Abstract: Laser flash photolysis was used to investigate the fast reaction of 4-(2- p -dimethylaminophenyl ethynil)-6,6-dimethyl-3-cyano-5,6-dihydro-2(1H)-pyridone (DHP) with the intermediate complex of platinum(III), PtCl 2− 5 , appearing in the photoreduction of PtCl 2− 6 in methanol. Kinetic and spectroscopic parameters of the new-formed complex PtCl 2− 5 |DHP were determined. DHP in this complex is coordinated by an −N(CH 3 ) 2 group nitrogen atom since a similar molecule with this group substituted by −O(CH 3 ) does not react with PtCl 2− 5 . Steady-state photolysis has shown that the transformation Pt(III) a Pt(II) involves escape of DHP from the coordination sphere since the final complex Pt(II)|DHP is not formed.
5 citations
TL;DR: The paramagnetic complex salt of diprotonated dioxocyclam (1,11-dihydro-5,7-dioxo-1,4,8,11tetra-azacyclotetradecane), Pt(II) tetrachloride and water has been synthesized in strongly acidic medium and identified by X-ray structure analysis as discussed by the authors.
Abstract: The paramagnetic complex salt of diprotonated dioxocyclam (1,11-dihydro-5,7-dioxo-1,4,8,11tetra-azacyclotetradecane), Pt(II) tetrachloride and water has been synthesized in strongly acidic medium and identified by X-ray structure analysis. The crystals of [(C10H22N4O2)2+(PtCl4)2−]·H2O are monoclinic, space groupP21c,Mr=585.23,a=9.516(1) A,b=11.926(1) A,c=16.622(2) A,β=102.88(2)°,V=1839(1)A3,Z=4,Dx=2.114 g cm−3, λ(MoKα)=0.70930 A,μ=83.1 cm−1,F(000)=1128,T=292 K,R=0.019 for 2808 observed reflections withI > 3δ(I). Alternating moieties of diprotonated dioxocyclam and a PtCl 2− 4 anion form columns running down the c axis. Water molecules are localized in the intercolumnar space and contribute to the extensive hydrogen bond network. The macrocycle conformation is characterized by two sequences of torsional angles, corresponding to two different subunits. The shorter sequence idealized as (-sc, ap, -ac, + ac, ap, +sc) [sc( ±60°), ac( ±120°), ap(180°)], describing the C pseudosymmetric part of the molecule, is centered on a -CH2 group between the two peptide O-C-N-H fragments. The opposite C pseudosymmetric subunit has a nearly (-sc, ac, -SC, ap)2 conformation. Pt is square planar coordinated by four Cl atoms, Pt-Clαve = 2.306(8) A. The shortest Pt ... Pt distance is 7.200(1) A.
2 citations