Authors:Edward Krzyżak, Alina Wojakowska, Andrzej Wojakowski, and Marek Wołcyrz
Phase diagram for the system CuBr–LiBr was determined by differential scanning calorimetry and X-ray powder diffraction. The
system exhibits a significant solid solubility of the components, especially LiBr in the respective polymorphic modifications
of CuBr. Another feature of the system CuBr–LiBr is the occurrence of five invariant three-phase equilibria, which have been
assigned to one eutectic (684 K), one peritectoid (668 K), and three eutectoids (679, 645, and 521 K). From the experimental
results, formation of a compound LiCuBr2, at 521 K is discerned.
The phase diagram for the CuBr−TlBr system was investigated using the differential thermal analysis completed by the X-ray
powder diffraction data. Three intermediate phases were found: Tl2CuBr3 (stable from room temperature up to 234°C where decomposes in the solid state), Tl3Cu2Br5 (stable between 168°C and its incongruent melting point 262°C) and a nonstochiometric δ phase (centered about 75 mol% CuBr
and stable above about 240°C).
Authors:Z. Lu, Y. Ding, Y. Xu, Z. Yao, Q. Liu, and J. Lang
Thermal analysis on two new heterometallic sulfide clusters, [PPh4]2[WS3(CuBr)3]2 and [PPh4]2[MoS3(CuBr)3]2 (where PPh4=tetraphenyl
phosphonium, =pentamethylcyclopenta- dienyl), was carried out using a simultaneous TG-DTA unit in an atmosphere of flowing
nitrogen and at various heating rates. Supplemented using EDS method, their thermal behavior and properties, together with
the composition of their intermediate product, were examined and discussed in connection with their distinctive molecular
structure as a dianion, which provided some theoretically and practically significant information. Both clusters decomposed
in a two-step mode, but without a stable new phase composed of Mo/W-Cu-S formed during their decomposition process as we expected.
Based on TG-DTG data, four methods, i.e. Achar-Brindley-Sharp, Coats-Redfern, Kissinger and Flynn- Wall-Ozawa equation, were
used to calculate the non-isothermal kinetic parameters and to determine the most probable mechanisms.
Differential scanning calorimetric measurements have been carried out for Cul, CuBr, Agl, Ag2S, NaNO2, NaNO3 and KSCN. First-order phase transformations occur with the compounds Cul, CuBr, Agl and Ag2S; NaNO2, NaNO3 and KSCN exhibit λ-type transformations. The enthalpy changes due to phase transitions have been determined. Thermal hysteresis exhibited by these compounds have been examined in the light of their change in unit cell volumes.
Authors:H. Langfelderová, D. Makáová, and V. Jorík
Thermal decomposition of [Cu4O(Cl+Br)6(OPPh3)4], starts at temperatures about 200°C. The decomposition proceeds in several steps. The intermediate formed in the first decomposition
step (weight loss 2–4%) is a new crystalline phase with slightly different structure but with preserved central unit Cu4O. The only crystalline phases found in the further decomposition products was CuBr in all cases when the bromine atoms were
present, the presence of CuCl was only observed at the decomposition of the hexachlorocomplex.
Authors:V. Leovac, R. Petković, A. Kovács, G. Pokol, and Katalin Szécsényi
Factors determining the complex formation reaction of copper(II), nickel(II) and cobalt(II) chloride and copper(II) bromide
with 3,5-dimethyl-1-(hydroxymethyl)-pyrazole (HL) has been studied. Depending on experimental conditions, complexes with different
composition were obtained: [CuCl2(dmp)]2 (I), [CuCl2(dmp)2]2 (II), [CoCl2(dmp)2] (III) (dmp=3,5-dimethylpyrazole), [CuBr(L)]2 (IV), [CoCl(L)(EtOH)]4 (V) and [NiCl(L)(EtOH)]4 (VI). The compounds were characterized by FTIR spectroscopy, solution conductivity and magnetic measurements. The crystal structure
of [CoCl(L)(EtOH)]4 has been determined by single crystal X-ray diffraction. The thermal decomposition of the compounds was studied and found
to be continuous for all of the compounds. The desolvation mechanism of [MCl(L)(EtOH)]4 (M=Co(II), Ni(II)) is explained on the basis of the route of complex formation of CoCl2 with HL.
Authors:Vinay Bhaya, Ramesh Joshi, and Amol Kulkarni
The continuous-flow Meerwein arylation is demonstrated for a set of few aryl donors (anilines and m-aminoacetophenone) and specific radical acceptors. Homogeneous catalyst (CuBr in HBr and CuCl in HCl) was used to facilitate the reaction. The effect of parameters, viz., temperature, catalyst concentration, residence time, and concentration of the radical acceptor on the yield of the arylated product, was studied. The yield of the aryl derivative obtained by continuous-flow syntheses was always better than the respective experiments in batch mode. Flow synthesis allows easy variation in these parameters and thus allows going close to the maximum possible yields in a system where the relative rates of different reactions create a complex situation. Temperature plays a crucial role by affecting the rates as well as by governing the system homogeneity. The nitrogen bubbles generated in the reaction helped to avoid any channel blockage.
Authors:P. Aslanidis, V. Gaki, K. Chrissafis, and M. Lalia-Kantouri
[CuXL 2 ] 2 (1–4)
The complexes were prepared according to published procedures [ 6 , 7 ] , in some cases slightly modified. A suspension of 0.5 mmol of copper(I) halide (49.5 mg for CuCl, 71.7 mg for CuBr) in 50 cm 3 of dry acetonitrile