IR study of the structure of palladium(II) acetate in chloroform, acetic acid, and their mixtures in solution and in liquid-solid subsurface layers

It is found that cyclic trimer I and linear dimer II are the molecular stat es of palladium(II) acetate in its 1.10(-3)-0.7 M chloroform solutions. The mole fraction of dimer II is higher in dilute solutions. Even with small a cetic acid (HOAc) additions the I <----> II equilibrium is shifted toward I because of the variation of the composition of the outer-spheric solvation shells. The content of II in the 0.1 M solution of PdAc2 in 50 vol. % HOAc +CHCl3 is 10%. However, in the thin subsurface layers of this solution at t he interface CaF2-solution, the I <----> II equilibrium is slowly shifted t oward II whose concentration after 60 min is 22%. This may be caused by str ucturing of the liquid phase in the subsurface layers during rite measured time.