Formation of N-2-hydroxyalkylpyridine-2-carboxamidines in the coordination sphere of copper(II).: The crystal structure of dibromo-bis(N-2-hydroxypropylpyridine-2-carboxamidine-N,N′) copper(II)

Condensation of pyridine-2-carbonitrile (2-CNpy) with 2-aminoethanol (L1) or 1-amino-2-propanol (L2) in ethanolic solutions of CuX2 (X=Cl or Br) proceeds readily under mild reaction conditions to form stable solid complexes of composition [CuX2(amL-NH)2]·nH2O (n=0–2) which contain the imino form of N-2-hydroxyalkylpyridine-2-carboxamidines (amL-NH). The crystal structure of dibromo-bis(N-2-hydroxypropyl-pyridine-2-carboxamidine-N,N′) copper(II) and IR data confirm bidentate N,N-coordination of N-2-hydroxyalkylpyridine-2-carboxamidines (via the nitrogen atom of the pyridine ring as well as via the nitrogen atom of the terminal imino group). On the other hand, the complex of composition [CuCl2(amL1-NH2)] contains only a terdentate N,N,O-coordinated amino form of N-2-hydroxyethylpyridine-2-carboxamidine (amL1-NH2) molecules as organic ligands. Based on the molecular structure the electronic, IR and conductometric measurements are discussed.