Synthesis and structural diversity of 2-pyridylmethylideneamine complexes of zinc(II) chloride

The addition reactions of zinc(II) chloride to N-substituted pyridine-2-carbaldimines [Py–CHNR, R = Me (1a), Ph (1b), Bz (1c), allyl (1d)] lead to different complexes dependent on the N-bound substituent R. The 1:1 complexes show molecular structures of the type [(Py–CHNR)ZnCl2] for R = methyl (2a), phenyl (2b), and allyl (2d) with a distorted tetrahedral environment for the zinc atom. The zinc complex with the N-methylated pyridine-2-carbaldimine also forms a dimer of the type [(Py–CHNR)ZnCl2]2 (2a)2 with a square pyramidal coordination sphere of zinc. A 3:2 stoichiometry is observed for R = benzyl and an ion pair of the type [Zn(Py–CHNR)3]2+ [ZnCl4]2− (2c) is found in the solid state.

Graphical abstractThe molecular structures of 2-pyridylmethylideneamine complexes of zinc(II) chloride strongly depend on the N-bound group R thus yielding complexes of the types [(Py-CH7NR)ZnCl2] (A), [(Py–CHNR)ZnCl2]2 (A)2, and [(Py–CHNR)3Zn][ZnCl4] (B). With methyl substituted ligands, mono- and dinuclear complexes co-crystallize (see picture).Figure optionsDownload full-size imageDownload as PowerPoint slide