Reversible Formation and Transmetalation of Schiff-Base Complexes in Subcomponent Self-Assembly Reactions

Pinuclear complexes [Zn-2(NS,NS)(2)] 3 and [Ni-2(NS,NS)(2)] 6 bearing Schiff-base ligands featuring two NS donor groups were,obtained in subcomponent self-assembly reactions using nickel or zinc as template metals. Several transmetalation reactions starting from 3 or 6 yielded the complexes [Pd-2(NS,NS)(2)] 4 and [Co-2(NS,NS)(2)] 5, and their molecular structures were determined by X-ray diffraction. Starting from the Mononuclear complex [Ni(NS/NOH)(2)] 9 featuring a coordinated NS Schiff base and a free NOH Schiff base, completely reversible thermodynamically controlled imine bond formation was observed leading to complex [Ni-2(NS,NS)(2)] 6 and the free Schiff -base ligand NOH,NOH 10.