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

Dinuclear complexes [Zn2(NS,NS)2] 3 and [Ni2(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
[Pd2(NS,NS)2] 4 and [Co2(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 [Ni2(NS,NS)2] 6 and the free Schiff -base
ligand NOH,NOH 10.