ИСТИНА

In this work we have studied the electrochemical behaviour of cryptand [2.2.2.] in 10-2M MgSO4 solution with using Hg-electrodes (dropping and stationary). The investigations were carried out by the impedance, polarographic and voltamperometric methods. Taking into account, that in the investigated system the concentration ratio of free cryptand [2.2.2.] and its complex with Mg2+ is equal 100, we can believe, that at the positive charges of electrode surface adsorption phenomena have been determined by adsorption of neutral ligand molecules. Analysis of these and formerly received by us data shows, that adsorbed layer, forming at more positive charges of electrode surface, has more dense packing and more strong attraction between molecules in comparison with layers of cationic complexes and of Cr molecules, forming at negative charges. It can be explained by orientation of spheroidal Cr molecules with N-atoms to electrode surface. Such orientation provides the most regulated arrangement of these molecules in adsorbed layer. The area occupied by adsorbed Cr molecule (0.49 nm2) close to area of its cross-section ( 0.43 nm2). It was established, that in solutions with Cr electrochemical reaction takes place in the region of negative potentials (E  -1.7 V s.c.e.). The mechanism of this process was studied by polarographic and voltamperometric methods. It was shown that this cathodic process is catalytic evolution of hydrogen with participation of Cr molecule.