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The First Sodium Uranyl Chromate, Na 4 [(UO 2 )(CrO 4 ) 3 ]: Synthesis and Crystal Structure Determination
Author(s) -
Krivovichev Sergey V.,
Burns Peter C.
Publication year - 2003
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200300109
Subject(s) - uranyl , triclinic crystal system , crystallography , bipyramid , chromate conversion coating , tetrahedron , chemistry , crystal structure , pentagonal bipyramidal molecular geometry , sodium , materials science , uranium , chromium , metallurgy , organic chemistry
The first sodium uranyl chromate, Na 4 [(UO 2 )(CrO 4 ) 3 ], has been obtained by high‐temperature solid‐state reaction. The structure (triclinic, P 1¯, Z = 2, a = 7.1548(3), b = 8.4420(3), c = 11.5102(5)Å, α = 80.203(1)°, β = 79.310(1)°, γ = 70.415(1)° V = 639.24(4)Å 3 ) has been solved by direct methods and refined on the basis of F 2 for all unique reflections to R 1 = 0.024 [calculated on the basis of 4374 unique observed reflections (‖ F o ‖ 4σ F )]. The structure is based on chains of composition [(UO 2 )(CrO 4 ) 3 ] that are parallel to [1¯01]. The chains contain Ur O 5 pentagonal bipyramids ( Ur = Uranyl) that share all equatorial corners with CrO 4 tetrahedra. Cr(1)O 4 and Cr(3)O 4 tetrahedra bridge between two adjacent Ur O 5 bipyramids, whereas Cr(2)O 4 tetrahedra share one corner with one Ur O 5 bipyramid each. The [(UO 2 )(CrO 4 ) 3 ] chains are planar and oriented parallel to (313). The Na + cations provide linkage of the chains in the structure.