Some regularities of the ionic dissociation of complexes of aluminum compounds with electron donors

Modeling the formation of ions in AIRS -electron donor (L)-organic solvent systems (R is an alkyl radical or a halogen atom) specified the conditions under which the concentration of ions sharply changes with increasing ain the vicinity a = [L]/[AlR 3 ] = 1. The point a = 1 plays a special role because, at a 1, the concentration of free L molecules rapidly increases with a, thereby shifting the other equilibria in the system. The cases when water is absent or present in amounts small compared to AlR 3 were considered. It was established that when ions are formed from the main components (L and AlR 3 ) in the absence of water or when the water is not bound into H 2 O . AlR 3 and L x . H 2 O . AlR 3 , x = 1, 2) complexes, the concentration of ions passes through a flat maximum at a 1. The formation of L x . H 2 O . AIRS complexes can manifest itself as a sharp (or even steeplelike) peak in the dependence of concentration of ions in the vicinity of a = 1, a phenomenon that was observed experimentally. Another mechanism by which the concentration of ions drops in the vicinity of a = I and at a > I is the hydrolysis of AlR 3 . This process effectively prevents water from participating in the formation of ions. The structure and thermodynamic parameters of the neutral complexes formed in the solution were calculated for the AlMe 3 -pyridine-water system, as an example.