Highly Kinked Uranyl Chromate Nitrate Layers in the Crystal Structures of A[(UO2)(CrO4)(NO3)] (A = K,Rb)

Two first uranyl chromate nitrates, K[(UO₂)(CrO₄)(NO₃)] ( 1 ) and Rb[(UO₂)(CrO₄)(NO₃)] ( 2 ), were prepared by solid‐state reactions and characterized by electron microprobe analysis and single‐crystal X‐ray diffraction. The compounds are isotypic [ 1 : monoclinic, P2₁/c, a = 9.881(5), b = 7.215(4), c = 14.226(6) Å, β = 124.85(3)°, V = 832.3(7) ų; 2 : monoclinic, P2₁/c, a = 9.804(1), b = 7.359(1), c = 14.269(1) Å, β = 122.048(4), V = 872.6(1) ų]. The structures of 1 and 2 are based upon the complex [(UO₂)(CrO₄)(NO₃)]^– layers with unprecedented structural topology, which consist of the UrO₃NO₃ units linked through CrO₄ tetrahedra. The resulted kinked layer can be divided into chains arranged in the ladder fashion. The layers are parallel to (100) and are linked by A⁺ (A = K, Rb) cations located between the layers.