Synthesis and crystal structures of zirconium(IV) nitrate complexes (NO2)[Zr(NO3)3(H2O)3]2(NO3)3, Cs[Zr(NO3)5] and (NH4)[Zr(NO3)5](HNO3)

The zirconium nitrate complexes (NO2)[Zr(NO3)(3)(H2O)(3)](2)(NO3)(3) (1), Cs[Zr(NO3)(5)] (2), (NH4)[Zr(NO3)(5)](HNO3) (3), and (NO2)(0.23)(NO)(0.77)[Zr(NO3)(5)] (4) were prepared by crystallization from nitric acid solutions in the presence of H2SO4 or P2O5. The complexes were characterized by X-ray diffraction. The crystal structure of I consists of nitrate anions, nitronium cations, and [Zr(NO3)(3)(H2O)(3)](+) complex cations in which the Zr-IV atom is coordinated by three water molecules and three bidentate nitrate groups. The coordination polyhedron of the Zr-IV atom is a tricapped trigonal prism formed by nine oxygen atoms. The island structures of 2 and 3 contain [Zr(NO3)(5)](-) anions and Cs+ or NH4+ cations, respectively. In addition, complex 3 contains HNO3 molecules. Complex 4 differs from (NO2)[Zr(NO3)(5)] in that three-fourth of the nitronium cations in 4 are replaced by nitrosonium cations NO+, resulting in a decrease in the unit cell parameters. In the [Zr(NO3)(5)](-) anion involved in complexes 2-4, the Zr-IV atom is coordinated by five bidentate nitrate groups and has all unusually high coordination number of 10. The coordination polyhedron is a bicapped square antiprism.