Synthesis and Crystal Structure of a Uranyl Bichromate, [CH_(6)N_(3)]_(2)[(UO_(2))(CrO_(4))(Cr_(2)O_(7))](H_(2)O)

摘要

Crystals of the first uranyl bichromate, [CH_(6)N_(3)]_(2)[(UO_(2))(CrO_(4))(Cr_(2)O_(7))](H_(2)O), were obtained by evaporation from aqueous solutions. The compound crystallizes in the triclinic system, space group P1, a velence 7.1829(17), b velence 9.304(3), c velence 14.884(4) A, alpha velence 102.43(2) deg, beta velence 97.98(2) deg, gamma velence 101.07(2) deg, V velence 936.3(5) A~(3), Z velence 2. The structure was solved by direct methods and refined by the full-matrix least-squares method to R_(1) velence 0.064 (wR_(2) velence 0.138) for 2225 reflections with |F_(hkl)| >= 4sigma(|F_(hkl)|). The structure is based on infinite [(UO_(2))(CrO_(4))(Cr_(2)O_(7))]~(2-) chains where [UO_(7)]~(8-) pentagonal bipyramids are linked by tridentate [Cr(1)O_(4)]~(2-) groups and [Cr_(2)O_(7)]~(2-) groups; these chains run along x axis and are oriented parallel to (011). Trigonal [CH_(6)N_(3)]~(+) cations and water molecules are arranged between the chains.