Ján Garaj

COPPER(II) COORDINATION COMPOUNDS: CLASSIFICATION AND ANALYSIS OF CRYSTALLOGRAPHIC AND STRUCTURAL DATA III. DIMERIC COMPOUNDS

Abstract This review summarizes the data for over nine hundred dimeric Cu(II) coordination compounds. There are several types of the bridges, from which doubly bridges by far prevail. The most common ligands are O− and N− donors. From the stereochemical point of view, a square-pyramidal arrangement with different degrees of distortion about Cu(II), is the most common. Several relationships were found between the Cu-Cu distances and the Cu-L-Cu bridge angle and the type of bridging, between the intra-ligand L-Cu-L ring angles and coordination numbers.

The crystal structure of copper(I) thiocyanate and its relation to the crystal structure of copper(II) diammine dithiocyanate complex

Abstract Well developed crystals of copper(I) thiocyanate, CuNCS, are formed by decomposition of Cu(NH 3 ) 2 (NCS) 2 in aqueous solution. They belong to the orthorhombic system, the space group is Pbca, a = 10.994(9) A , b = 7.224(3) A ; c = 6.662(2) A , and there are eight formula units in a unit cell. The structure was refined by the method of full matrix least squares, yielding the value 0.062 for the R factor. All thiocyanate groups are approximately linear in the crystal structure and they are fourdentate, bonding in the form of bridges. Each copper atom is tetrahedrally coordinated by three sulphur atoms (the distances CuS being in the interval 2.34–2.37A) and by the nitrogen atom (CuN = 1.93 A). Each sulphur atom is tetrahedrally coordinated by three copper atoms and one carbon atom (SC = 1.70A). The relation between the crystal structures of Cu(NH 3 ) 2 (NCS) 2 and CuNCS are discussed.

On-line preconcentration of trace copper for flame atomic absorption spectrometry using a spherical cellulose sorbent with chemically bound quinolin-8-ol

Abstract Preconcentration was effected using a 50 mm × 2 mm i.d. minicolumn packed with a spherical cellulose sorbent with chemically bound quinolin-8-ol function groups (Ostorb Oxin). The column was connected to the nebulizer of the atomic absorption spectrometer and the sample solution and eluent (2 M hydrochloric acid) were sucked through it at a flow-rate of 2–3 ml min−1 by utilizing the negative pressure of the nebulizer. The experimental design was tested with the determination of traces of copper. Peak-area and peak-height measurements were compared. Owing to the simple calibration, the former method was used for quantification. The dynamic range was from 0.3 ng ml−1 (detection limit) to 5 μg ml−1 (breakthrough). The reproducibility in the concentration range 25 ng ml−1-5 μg ml−1 was better than 5%. Water-soluble inorganic salts, ammonia and sodium hydroxide were analysed. The accuracy of the results was checked by anodic-stripping voltammetry and by electrothermal AAS.

COMPUTER-ASSISTED OPTIMIZATION OF SELECTIVITY BY TUNING TEMPERATURE AND CARRIER GAS PRESSURE DROP IN TWO GC CAPILLARY COLUMNS COUPLED IN SERIES

The paper shows a computer-assisted procedure for the optimization of selectivity of two columns coupled in series by tuning the working temperature (using the isothermal mode) and columns coupling-point pressure at constant inlet and outlet carrier gas pressures. The optimization procedure validation was tested by the separation of 32 hydrocarbons in a column series with the aim to resolve the maximum number of components in the shortest possible analysis time.

Pre-concentration of trace metals from acidic sample solutions on a thin layer of activated carbon using dithizone as a chelating agent

Acidic sample solutions were analysed by flame AAS and spectrophotometry, making use of the collection of trace amounts of Ag, Bi, Cu, Cd, Hg, Pb and Zn as their dithizonates on a thin layer of activated carbon. The metal chelates were then released from the activated carbon layer by digestion with 14 M HNO3. The dependence of the trace element recoveries on the concentration of HNO3 and HCI in the sample solution was investigated. Water samples, aluminium, salts and acids were analysed and the accuracy of the results was checked by electrothermal AAS or by pre-concentration with a thiuram disulphide precipitate. The detection limits were between 0.3 ng ml–1(Cd) and 10 ng ml–1(Hg) and the relative standard deviations varied from 1 to 8%. The recovery, separation factor and pre-concentration factor of the method are discussed.

Kinetic study of Pt-cytostatics reactions by HPLC

HPLC with DAD (diode array detector) was applied as rapid method for the analytical control of the purity and stability of carboplatin and oxocarboplatin as effective cytostatics of 2nd generation. The stability of carboplatin has been measured in some infusion media (sodium chloride, glucose, sodium citrate) and compared to the cisplatin (cytostatic of 1st generation) stability. In addition ligand-exchange reactions between cisplatin and carboplatin have been studied together with the influence of temperature, pH and the concentrations of reactants. A method was developed for the analysis of clinical samples using solid-phase extraction as a preseparation and preconcentration step. The detection limits were 5 μg/ml serum for cisplatin, 0.16 μg/ml for carboplatin and 0.23 μg/ml for oxo-carboplatin.

Spectrophotometric determination of trace amounts of copper after pre-concentration with thiuram disulphide

Copper can be determined spectrophotometrically as the complex copper(II) bis(pentamethylene dithiocarbamate) after pre-concentration by coprecipitation of the complex with thiuram disulphide. The statistical importance on copper recovery with preconcentration of pH, the amount of thiuram disulphide, the solution standing time with the precipitate and the solution temperature are tested by the method of full factorial experiments of the 2n type. The influence of Ni2+, Co2+, Fe2+/3+ and Mn2+ is removed by masking with EDTA at pH 5–8. The copper detection limit is approximately 3 µg dm–3 for water samples and 0.03 µg g–1 for solid samples.

Application of Fourier transformation in high resolution gas chromatographic trace analysis

Abstract The fast Fourier transformation (FFT) method was used to increase the signal-to-noise ratio (S/N) in high resolution gas chromatographic trace analysis. A new procedure has been devised for FFT smoothing of chromatograms with a very low S/N. The proposed FFT smoothing procedure allows improvement of S/N by a factor of twenty with a very low error of the peak area recovery.

Isomers of Organotin Compounds II. Di - to Polymeric Compounds

The dito polymeric organotin compounds cover a wide field, as shown by a recent survey covering the crystallographic and structure data of almost six hundred examples. About 10 % of these compounds exist as isomers and are summarised in this review. Included are distortion (92 %), ligand, cis trans, and η mer isomerism. These are discussed in terms of the coordination about the tin atom, and correlations are drawn between donor atom, bond length and bond angles. Distortion isomers, differing only by degree of distortion in Sn L distances and L Sn L angles, are the most common. The tin atoms are found in the oxidation states, Sn, Sn2 and Sn.

Polymeric triamminetetrakis(μ-cyano)-dicuprate(I)copper(II)

The crystal structure of the mixed-valence copper-cyanide complex [Cu I 2 Cu II (CN) 4 (NH 3 ) 3 ]∞ comprises infinite polymeric double chains. The geometry about the Cu I centres is approximately trigonal pyramidal, and each Cu II centre adopts a slightly distorted square-pyramidal coordination, with one NH 3 ligand disordered equally over two alternative sites. In contrast to previous reports, we find that the title compound crystallizes in the monoclinic space group P2 1 /n.