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))

摘要

Condensation of pyridine-2-carbonitrile (2-CNpy) with 2-aminoethanol (L~1) or 1-amino-2-propanol (L`2) in ethanolic solutions of CuX_2 (X = Cl or Br) proceeds readily under mild reaction conditions to form stable solid complexes of composition [CuX_2 (amL-NH)_2]·nH_2O (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-coordinatio 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 [CuCl_2(amL~1-NH_2)] contains only a terdentate N,N,O-coordinated amino form of N-2-hydroxyethylpyridine-2-carboxamidine (amL~1-NH_2) molecules as organic ligands. Based on the moleclar structure the electronic, IR and conductomeric measurements are discussed.