Crystal chemistry of thorium nitrates and chromates

The structures and infrared spectra of six novel thorium compounds are reported. Th(NO3)2(OH)2(H2O)2 (1) crystallizes in space group C2/c, a=14.050(1), b=8.992(7), c=5.954(5) A, β=101.014(2)o. K2Th(NO3)6 (2), P-3, a=13.606(1), c=6.641(6) A. (C12H28N)2Th(NO3)6 (3), P21/c, a=14.643(4), b=15.772(5), c=22.316(5) A, β=131.01(1)o. KTh(NO3)5(H2O)2 (4), P21/c, a=10.070(8), b=12.731(9), c=13.231(8) A, β=128.647(4)o. Th(CrO4)2(H2O)2 (5), P21/n, a=12.731(1), b=9.469(8), c=12.972(1) A, β=91.793(2)o. K2Th3(CrO4)7(H2O)10 (6), Ama2, a=19.302(8), b=15.580(6), c=11.318(6) A. The coordination polyhedra about Th in these structures are diverse. Th is coordinated by 9 O atoms in 5 and 6, seven of which are from monodentate (CrO4) tetrahedra and two are (H2O). The Th in compound 1 is coordinated by ten O atoms, four of which are O atoms of two bidentate (NO3) triangles and six of which are (OH) and (H2O). In compounds 2, 3 and 4 the Th is coordinate by 12 O atoms. In 2 and 3 there are six bidentate (NO3) triangles, and in 4 ten of the O atoms are part of five bidentate (NO3) triangles and the others are (H2O) groups. The structural units of these compounds consist of a chain of thorium and nitrate polyhedra (1), isolated thorium hexanitrate clusters (2, 3), an isolated thorium pentanitrate dihydrate cluster (4), and a sheet (6) and framework (5) of thorium and chromate polyhedra. These structures illustrate the complexity inherent in the crystal chemistry of Th. - Graphical Abstract: The structures and infrared spectra of four new Th nitrates and two Th chromates are reported. The coordination numbers of the Th cations range from nine to 12 in these compounds. Structural units consist of isolated clusters, chains, sheets and frameworks.