Isoreticular 2D uranyl coordination polymers based on the mixed oxalate-succinate linkers

摘要

Two new oxalate-succinate uranium (VI) compounds with the guanidinium cations were synthesized and studied by single crystal X-ray diffraction, IR spectroscopy, thermogravimetric, and differential thermal analysis. The compounds are (CN_3H_6)_2[(UO_2)_2(oxal)(suc)_2]·4H_2O (1) and (CN_3H_6)_2[(UO_2)_2(oxal)_2(suc)]·2H_2O (2), where oxal = oxalate ion, C_2O_4~(2-) and suc = succinate ion, C_4H_4O_4~(2-) . Crystal structures of both phases include 2D [(UO_2)_2(L)_3]~(2-) complexes (L - dicarboxylate ion) with the same ‘graphite sheet' topological type. However, the coordination numbers of uranium in the sheets are different for the different oxalate: succinate ratio in formula (2:1 or 1:2). The coordination number preference (8 or 7) was found to depend on the oxalate: U(VI) ratio.