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Ligand substitution at a hexa-coordinate centre. Reaction of [Co2(Et2dtc)5]BF4 with some dithiooxamides. Part II. A kinetic study
No full textAdduct formation of some tris (N, N dialkyl-di thiocarbamato) Cr(III) complexes with iodine
No full textSpectrophotometric studies of dichloromethane solutions containing iodine and some Cr(S2CNR2)3 complexes (where R2NCS-2 are: OC4H8NCS-2 = modtc; (C2H5)2NCS-2 = Et2dtc; (C6H5CH2)2NCS-2 = Bz2dtc) have shown the formation of 1:1 adducts whose spectral features were studied and which suggested that charge-transfer interaction involving iodine and a sulphur atom of a coordinated dithiocarbamato ligand occurred. A new BASIC non-linear least-squares program which performs an optimization of the absorbance data taken at several wavelengths was devised to evaluate reliable formation constants. The thermodynamic parameters have been calculated and compared with those obtained in the same conditions as above by a reinvestigation of the known 1:1 complex formation of iodine with the corresponding tetraalkylthiuram-disulphides, where the donor site is also the sulphur atom of the thiocarbonyl group. The -ΔH° values related to the Cr(dtc)3 · I2 complexes are about 2 kcal lower than those of thiuram disulphides, showing a lowering of the donor strength of the thiocarbonyl sulphur as a consequence of the coordination to the metal. © 1984
Recupero dei metalli nobili da schede elettroniche (PCB): un approccio multidisciplinare verso la sostenibilità
No full textNoble-metals recovery from printed circuit boards: a multidisciplinary approach towards sustainability
No full textA robust database of the noble metals (NM) content of different classes of Printed
Circuit Boards (PCB) was build through an accurate characterization of samples of different
origin, underwent mechanical comminution and representative sampling, by ICP-AES
quantitative chemical analysis, to work as reference for researcher and companies interested in
waste valorisation. The results identified RAM and mobile phone’s PCB as the “richest” classes
of PCB, while TV PCB as the “poorest” in term of NM content. On these basis, a sustainable
three-step NM recovery method, previously set-up on a finely shredded WEEE sample deprived
by non-metallic and ferrous materials, was applied on a coarse sample of shredded RAM
boards provided by companies, as a case study. Preliminary results highlighted that good NM
recovery yields (from 65% to quantitative) and limited by-products formation could be achieved,
despite a huge amount of composite materials was present in the mixture. Nevertheless, 10-
times increased leaching times found for copper dissolution suggested that improved
mechanical pretreatments might increase leaching effectiveness
On the anomalous magnetic properties of tris(diselenocarbamato)iron(III) compounds
No full textAn extended magnetic investigation of a series of pseudo-octahedral [Fe(Se2CNR2)3] compounds [R2 = piperidino, morpholino, thiomorpholino, Bu2, Et2, (PhCH2)2, (C6H13)2, and MePh] has been made at 90-400 K. Diamagnetic compounds not containing iron, Se(Se2CNEt2)2, Se[Se2CN(CH2Ph)2]2, and (Se2CNMePh)2, have also been isolated and their presence could explain the previously reported low-spin classification of [Fe(Se2CNR2)3] compounds. The reported measurements demonstrate that the magnetic behaviour of these compounds is anomalous, the μ values generally ranging between the limiting values typical for 6A1 and 2T2 states. Treatment of the experimental values by means of van Vleck's equation has enabled the evaluation of the crossover parameters, and a full comparison with the dithiocarbamate derivatives is made. The influence of the substituents on the nitrogen of the ligand on the position of the spin equilibrium is discussed
Nickel dithiolene complexes as a source of a new family of S,S-dinegative chiral ligands R4btimdt = 5,5’-bis(1,3-dialkyl-4-imidazolidine-2-thione-4-thiolate
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
New semiconductors obtained by reaction of 4-imidazoline-2-selone derivatives with TCNQ. Characterization and X-ray structure of (C<SUB>9</SUB>H<SUB>12</SUB>N<SUB>4</SUB>Se)(TCNQ)<SUB>3</SUB>
No full textJ.MATER. CHEM
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