Ab initio studies of the structure, physicochemical properties and behavior of lead chlorides and chloroplumbate anions in gaseous and aqueous phases

Ab initio studies of the structure and physicochemical properties of lead chlorides (PbClx; x = 1 − 5) and their chloroplumbate derivatives ( PbCl y n - ; y = 1 − 7, n = 1 − 4), as well as the thermodynamics and kinetics of processes involving these entities, were carried out at the MP2 and MP2(PCM) levels of theory. The following appeared to be electronically stable: isolated lead chlorides in which x = 1 − 5, singly charged anions (n = 1) in which x = 1 − 6 and doubly charged anions (n = 2) in which y = 4 − 6, and additionally PbCl 5 3 - , PbCl 6 3 - , PbCl 6 4 - and PbCl 7 2 - in the aqueous phase. Spontaneous reactions in the Pb/Cl2/Cl− system led to PbClx (x = 1 − 4) and PbCl y - (y = 2 − 5) in the gaseous phase, and also PbCl y 2 - (y = 4 − 6), PbCl y 3 - (y = 5, 6) and PbCl 6 4 - in the aqueous phase. The attachment of Cl− to neutral molecules was free of any kinetic activation barrier, whereas attachment to anions required a moderate activation barrier to be overcome. Cl2 reacts via a consecutive two-step process: complex formation, followed by unconcerted substitution.