THE ANIONS [(ZROH(CO)(3))(3)](6-) AND [(ZROH(C2O4)(3))(2)](6-) - SINGLE-CRYSTAL X-RAY-DIFFRACTION STUDIES OF THE COMPLEXES GUANIDINIUM ZIRCONIUM CARBONATE [(C(NH2)(3))(3)ZROH(CO3)(3)CENTER-DOT-H2O](2) AND SODIUM ZIRCONIUM OXALATE NA-6(ZROH(C2O4)(3))(2)CENTER-DOT-7H(2)O

The complex [(C(NH2)(3))(3)ZrOH(CO3)(3). H2O](2) (A) has been shown by -means of a single crystal X-ray diffraction study to contain [C(NH2)( 3)](+) cations and dimeric anions of formulation [(ZrOH(CO3)(3))(2)](6 -). The anion is centrosymmetric with each metal being bonded to two b ridging OH groups and three chelating CO32- ions.The Zr atoms are thus eight coordinate with a dodecahedral environment. The Zr-O distances formed by the bridging OH groups are shorter than those formed through zirconium carbonate interactions. The non-bonded Zr Zr distance is 3. 47(2) Angstrom. An infrared spectroscopic investigation of A provides data which support the findings of the crystallographic study. Likewis e the complex Na-6(ZrOH(C2O4)(3))(2). 7H(2)O (B) contains the anion [( ZrOH(C2O4)(3))(2)](6-). This anion is structurally related to the anio n in A as each Zr atom has an eight-coordinate dodecahedral environmen t being bonded to two bridging OH groups and three chelating oxalate l igands, but has no imposed crystallographic symmetry. The Zr Zr non-bo nded distance is 3.50(1) Angstrom. The O-Zr-O bridge angles are 69.7(4 )degrees in A and 67.4(3)degrees in B. (C) 1998 Elsevier Science Ltd. All sights reserved.