A series of temperature-dependent Cd^II-complexes containing an important family of N-rich heterocycles from in situ conversion of pyridine-type Schiff base

An efficient method for the synthesis of a wide variety of N-rich heterocycles has been systematically explored. The synthetic protocol involves a solvothermal in situ metal-ligand reaction of pyridine-type Schiff base N-(2-pyridylmethyl)-pyridine-2-carbaldimine (L) with Cd²⁺ ions, resulting in the efficient formation of nine temperature-dependent Cd^II-complexes 1-9 supported by six types of N-rich heterocycles L^1-6. To the best of our knowledge, both the synthetic strategy with solvothermal in situ Cd^II-mediated Schiff base-conversion and N-rich heterocycle rings L^1-2 as well as cis-L⁶ are reported for the first time. Meanwhile, plausible in situ formation mechanisms of L^1-6 are also proposed.