No abstract

Using a technique of thermogravimetry and under N2 gas atmosphere from 25 to 600°C, the thermal behavior of Cr(NO 3 ) 3 ⋅9H 2 O was studied. The received products were investigated by XRD. Depending on the conditions of reaction (temperature, heating rate, mass of sample, surrounding atmosphere) thermal decomposition leads to chromium oxides Cr2O3, different size and porosity or specific area of the forming grains. Calculations related to mass loss were also reported.

The acidity constants of MNPPAP 1 were determined by potentiometric pH titration. The stability constants of the 1:1 complexes formed between M 2+ : Ca 2+ , Mg 2+ , Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ or Zn 2+ and MNPPAP 2 , were determined by potentiometric pH titration in aqueous solution (I = 0.1 M, NaNO 3 , 25˚C). The order of the stability constants was reported. It is shown that the stability of the binary M(MNPPAP) complexes is determined by the basicity of the carboxyl or amino group. All the stability constants reported in this work show the usual trend. The obtained order is Ca 2+ < Mg 2+ > Mn 2+  Co 2+  Ni 2+  Cu 2+  Zn 2+. The observed stability order for MNPPAP follows approximately the Irving-Williams sequence. It is shown that regarding to M ion-binding properties vital differences on complex bilding were considered. It is demonstrated, that in M-MNPPAP complexes, M ion is coordinated to the carboxyl group, M ion is also able to bild macrochelate over pyrimidine group. The up-mentioned results demonstrate that for M-MNPPAP complex the stability constants is also largely determined by the affinity of M 2+ for carboxyl group. It is shown that MNPPAP can exert a direct influence on reaction mechanism through different kinds of metal ions and donor groups of MNPPAP.

The stability constants of the 1:1 complexes formed between M 2+ (M 2+ : Mn 2+ , Ni 2+ , Cu 2+ , or Cd 2+ ) and BMADA 2− (BMADA: 2,2'-(5-bromo-6-methylpyrimidine-2,4 diyl)bis(azanediyl)dipropanoic acid) were determined by potentiometric pH titration in aqueous solution (I = 0.1 mol L −1 , NaNO 3 , 25 °C). The stability of the binary M-BMADA complexes is determined by the basicity of the carboxyl or amino groups. All the stability constants reported in this work exhibit the usual trend, and the order obtained was. The observed stability order for BMADA approximately follows the Irving-Williams sequence. In the M-BMADA complexes, the M ion is able to form a macrochelate via the pyrimidine group of BMADA.