Synthesis, crystal structure and spectroscopy of catena-poly-bis(azido-N1,N1)(2-Aminopyrimidine)Copper(II)

摘要

The compound [Cu(ampym)(mu(1,1)-N-3)(2)](n) (ampym = 2-aminopyrimidine) has been synthesized and characterized by X-ray crystallography and infrared spectroscopy. In addition, Ligand Field and powder EPR measurements have been performed. The structure is solved in space group P21/c with a = 7.303(2), b = 19.716(4), c = 5.949(1) angstrom, beta = 98.17(3), V = 847.9(3) angstrom(3), Z = 2 with final R = 0.0382. The coordination geometry around the Cu(II) ion is distorted square pyramidal, with four nitrogen atoms of four bridging azido anions in the basal plane with Cu-N distances that range from 1.998(3) to 2.069(3) angstrom. The apical position is occupied by a nitrogen atom of the ampym molecule at a Cu-N distance of 2.169(3) angstrom. The trans-basal angles are 165.7(1) and 143.9(1)degrees. Weak hydrogen bonding is observed between the two amine hydrogen atoms and nitrogen of an azide anion and the pyrimidine-ring nitrogen atom of a neighbouring molecule (N center dot center dot center dot N distances 3.174(5), 3.106(4) angstrom). These last hydrogen bonds (N7 center dot center dot center dot N3) are forming so-called "Watson-Crick type" hydrogen bonds. In the infrared the vibrations of the coordinated azide anion are observed at 2,062, 1,273 and 655 cm(-1), while the Cu-N vibrations are observed at 370 and 224 cm(-1). Ligand-field and EPR spectra are uneventful and give spectral parameters expected in the range for such Cu(II) compounds. Magnetic susceptibility measurements reveal a weak antiferromagnetic interaction between the Cu(II) ions.