Structure of hexaaquacopper(II) bromate.

Abstract

[Cu(H2O)6](BrO3)2, Mr = 427.44, cubic, Pa3, a = 10.3240 (6) A, V = 1100.38 (4) A3, Z = 4, Dx = 2.580 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 92.32 cm-1, F(000) = 828, T = 296 K, R = 0.038 for 336 unique reflections having I greater than sigma I. The single type of copper ion (site symmetry 3) is coordinated by six water-molecule O atoms, each at an observed distance of 2.079 (4) A, in an array which is virtually regular octahedral, the nominal 90 degree angles measuring 89.95 (15) and 90.05 (15) degrees. Thus, this is not a typical CuII complex in which (consistent with a static Jahn-Teller effect) a distorted octahedral array displays '(2 + 2 + 2)' coordination; rather, it is the sixth strict example of a CuII static structure inconsistent with the Jahn-Teller theorem. The presence of a dynamic Jahn-Teller effect is supported by the data. The single type of bromate ion has an observed Br-O bond length 1.649 (3) A and O-Br-O bond angle 104.17 (15) degrees. The bromate ion was found to manifest rigid-body behavior but, consistent with a dynamic Jahn-Teller effect, the copper-oxygen complex did not. The Br-O bond length corrected for rigid-body motion is 1.663 A. Refinement of the positional parameters of the two inequivalent H atoms permitted a detailed analysis of hydrogen bonding, which occurs principally between the oxygen octahedra and the bromate groups.(ABSTRACT TRUNCATED AT 250 WORDS)