STRUCTURE OF HEXAAQUACOBALT(II) BROMATE

[Co(H2O)6](BrO3)2, M(r) = 422.83, cubic, Pa3BAR, a = 10.3505 (7)-angstrom, V = 1108.88 (8)-angstrom-3, Z = 4, D(x) = 2.53 g cm-3, lambda-(Mo K-alphaBAR) = 0.71069-angstrom, mu = 87.31 cm-1, F(000) = 820, T = 296 K, R = 0.027 for 365 unique reflections having I > sigma-I. The single type of Co ion is coordinated by six water-molecule O atoms, each at an observed distance 2.095 (2)-angstrom, in an array which is regular octahedral within the estimated standard deviations of the relevant angles. The single type of bromate ion has a Br-O bond length 1.653 (2)-angstrom and O-Br-O bond angle 104.07 (9)-degrees. The cobalt-oxygen complex manifested rigid-body behavior, but the bromate ion did not. The cobalt-oxygen distance corrected for rigid-body motion is 2.099-angstrom. Location and refinement of the two inequivalent H atoms permitted detailed analysis of the hydrogen bonding, which occurs principally between the oxygen octahedra and the bromate groups. This structure is isomorphic to that of hexaaquanickel(II) chlorate recently reported from this laboratory.