Formation of 2-pyridinyl-2-oxazolines and pyridine-2-carboxamidine in the coordination sphere of copper(II)

The reaction of pyridine-2-carbonitrile (2-CNpy) with 2-amino-2-hydroxymeth yl-1,3-propanediol (L-1) and 2-amino-2-methyl-1-propanol (L-2) in methanoli c solutions of anhydrous copper(II) chloride at room temperature led to the formation of solid complexes containing 2-(2-pyridinyl)-4,4-bis(hydroxymet hyl)-2-oxazoline (pyoxaL(1)) and 2-(2-pyridinyl)-4,4-dimethyl-2-oxazoline ( pyoxaL(2)), respectively. With copper(II) bromide instead of copper(II) chl oride, along with the oxazoline complexes, the complex dibromo-bis(pyridine -2-carboxamidine)copper(II) was isolated. Under several hour reflux, the co mplexes dihalogenobis(pyridine-2-carboxamidine)copper(IT) are the only isol able products both for chloride and bromide starting salts. The stereochemi stry of the complexes and the mode of ligand coordination have been determi ned by spectroscopic and conductometric measurements. The crystal structure of bromobis[(2-(2-pyridinyl)-4,4-dimethyl)-2-oxazoline]copper(II) bromide hydrate was solved by X-ray diffraction techniques. The mechanism of 2-CNpy transformation to the final products is proposed.