CdII-Mediated Efficient Synthesis and Complexation of Asymmetric Tetra-(2-pyridine)-Substituted Imidazolidine

Abstract

One convenient CdII-mediated C–C/C–N bond-forming strategy toward asymmetric tetra-(2-pyridine)-substituted imidazolidine (L1), the basic framework of several natural products with bioactivity, has been found for the first time. In the reaction of tridentate N3-set neutral pyridine-type Schiff base ligand (L) possessing a [−HCNCH2−] linkage with CdCl2 at 70 °C for 3 days, one two-dimensional 44 topological layer [Cd3L1Cl6]n (1) could be obtained, in which ligand L1 resulted from [3 + 2] C–C/C–N asymmetric coupling dimerization of L. When equimolar amounts of NaSCN and NaNO3 were added to the reaction mixtures, one-dimensional chain [Cd2L1(SCN)Cl3]n (2) and zero-dimensional dinuclear Cd2L1(NO3)4(MeOH) (3) containing the same ligand L1 were also generated under the same reaction conditions, respectively. Obviously, the medium of the Cd2+ ion plays the key role in solvothermal in situ formation of ligand L1. Moreover, new ligand tetra-substituted imidazolidine (L1) could be obtained effectually from all three complexes 1–3 through the reactions of those compounds with Na2S.