Rutherfordine, UO2CO3, is orthorhombic, a 4.840(1), b 9.273(2), c 4.298(1)
Angstrom, V 192.90(7) Angstrom(3), space group Imm2, Z = 2. The structure w
as refined to an R index of 2.2% on the basis of 306 unique data [\F-o\/sig
ma(\F-o\) > 5] measured with MoK alpha X-radiation on a single-crystal diff
ractometer. The structure consists of neutral sheets of edge- and corner-sh
aring (UO8) hexagonal bipyramids and (CO3) triangles, as originally propose
d by Christ et al. (1955); our refinement, however, shows that (CO3) groups
in alternate layers have the same orientation, not opposite orientations a
s originally reported. The refined value of the U-O(uranyl) distance is str
ongly affected by the details of the absorption correction, ranging from 1.
71 to 1.80 a as a function of the plate-glancing angle used in an empirical
psi-scan absorption correction and as a function of the type of weighting
scheme used in the refinement. The Gaussian-quadrature method of integratio
n also shows similar problems, but they are less extreme. The preferred val
ue for the U-O(uranyl) distance in rutherfordine is similar to 1.745 Angstr
om; as rutherfordine contains no H atoms, the O(uranyl) atom is [1]coordina
ted, and should have the shortest U-O(uranyl) distance stereochemically pos
sible. The current work suggests that U-O(uranyl) values less than 1.745 An
gstrom reported in other studies are adversely affected by less-than-optimu
m absorption corrections.