Crystal structures and photoluminescence of the Zn(II) and Cd(II) complexes of N-methylpyrazinium obtained by a less hazardous approach

Compared to previously reported methods, a less hazardous approach has been used to synthesize N-methylpyrazinium cation (mpz+) by the reaction of pyrazine and ClCH2COONa. Although a few mpz+-containing complexes have been documented, there is no example of mpz+-containing group IIB metal complexes. Three novel complexes containing mpz+, (mpz)ZnI3 (1), [(mpz)CdCl3]n (2), and [(mpz)CdBr3]n (3), have been successfully obtained via a solution or hydrothermal method by reactions of ZnI2, CdCl2·2.5H2O, and CdBr2·4H2O with the mpz+ ligand, respectively. Complex 1 features an isolated structure, with each zinc atom coordinated by one mpz+ ligand and three terminal iodine atoms. The CD spectra of 1 reveal that it exhibits spontaneous resolution. Complexes 2 and 3 are isotypic, and exhibit chain structures made by linear arrays of Cd(II) bridged by halogen atoms. Photoluminescent analyses reveal that complexes 1–3 exhibit strong blue emissions originating from intra-ligand π–π∗ transition of the mpz+ ligand.