Azidokomplexe des Zirkoniums: ZrCl3N3, [ZrCl4N3]22⊝, [ZrCl4(N3)2]2⊝; die Kristallstruktur von (PPh4)2[ZrCl4N3]2

Azido Complexes of Zirconium: ZrCl₃N₃, ZrCl₄N₃]₂^2?, ZrCl₄(N₃)₂]^2?; Crystal Structure of (PPh₄)₂ ZrCl₄N₃]₂ Highly explosive ZrCl₃N₃ is formed by the reaction of ZrCl₄ with iodine azide in dichloromethane suspension. According to the i.r. spectra, the compound is polymeric by azide and chlorine bridges. Zirconium tetrachloride reacts with one and two moles of tetraphenylphosphonium azide respectively, forming the thermally and mechanically stable complexes (PPh₄)₂ZrCl₄N₃]₂ and (PPh₄)₂ZrCl₄(N₃)₂]. The crystal structure of (PPh₄)₂ZrCl₄N₃]₂ was determined by X-ray methods (1942 reflexions, R = 6.5%). The complex crystallizes in the monoclinic space group P2₁/n with two formula units per unit cell. The structure consists of tetraphenylphosphonium cations and dimeric anions ZrCl₄N₃]₂^2?, in which the Zr atoms are linked by the α-N atoms of the azide groups, forming a centrosymmetric Zr₂N₂ ring with symmetry D_2h. According to the i.r. spectra, the azide groups in the complex (PPh₄)₂ZrCl₄(N₃)₂] are covalently bonded at the Zr atom in trans positions.