CRYSTAL STRUCTURE OF A HEXANUCLEAR BASIC LEAD(2) PERCHLORATE HYDRATE - PB60(OH)6(CLO4)4.H20

The structure of Pb6O(OH)6(ClO4)4.H2O has been determined by single-crystal X-ray diffraction. The crystals are orthorhombic, space group Pbca, Z = 8, a = 10.814 ± 0.005 Å, b = 16.706 ± 0.006 Å, c = 26.273 ± 0.008 Å, dx = 4.973 g/cm3, dm = 5.07 + 0.03 g/cm3. The structure was refined to a conventional R factor of 5.5%:, using 791 intensities which were collected by counter methods. The crystal contains discrete Pb6O(OH)64+ units. Four of the lead atoms are found in a central tetrahedron (distorted) while the remaining two cover two of the tetrahedral faces, thereby forming two exterior tetrahedra. The adjacent Pb-Pb distances average 3.81 Å and range from 3.44 to 4.09 Å. A unique oxygen atom (oxide) is found at the center of the central lead tetrahedron. The remaining six oxygen atoms, presumably hydroxide, are located over the six external faces of the two exterior lead tetrahedra. These results contradict an earlier conclusion from Raman evidence that the lead atoms are at the corners of an octahedron. © 1969, American Chemical Society. All rights reserved.