STRUCTURE OF HEXAAQUANICKEL(II) BROMATE

[Ni(H2O)6](BrO3)2, M(r) = 422.60, cubic, Pa3BAR, a = 10.2987 (6) angstrom, V = 1092.3 (2) angstrom 3, Z = 4, F(000) = 824, D(x) = 2.57 g cm-3, lambda(Mo K-alphaBAR) = 0.71073 angstrom, mu = 90.79 cm-1, T = 296 K, R = 0.024 for 360 unique reflections having I > sigma-I. The single type of nickel ion is coordinated by six water-molecule O atoms, each at an observed distance of 2.061 (2) angstrom, in an almost regular octahedral array. The single type of bromate ion has an observed Br-O bond length of 1.655 (2) angstrom and O-Br-O bond angle 104.25 (9)-degrees. Both the nickel-oxygen complex and the bromate ion were found to manifest rigid-body behavior. The Ni-O distance corrected for rigid-body motion is 2.065 angstrom, while the corrected Br-O bond length is 1.663 angstrom. Location and refinement of the two inequivalent H atoms permitted a detailed analysis of the hydrogen bonding, which occurs principally between the oxygen octahedron and the bromate groups. This structure is isomorphic to the structures of hexaaquanickel(II) chlorate and hexaaquacobalt(II) bromate which have been reported recently from this laboratory.