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) Å, β=101.014(2)°. K2Th(NO3)6 (2), P-3, a=13.606(1), c=6.641(6) Å. (C12H28N)2Th(NO3)6 (3), P21/c, a=14.643(4), b=15.772(5), c=22.316(5) Å, β=131.01(1)°. KTh(NO3)5(H2O)2 (4), P21/c, a=10.070(8), b=12.731(9), c=13.231(8) Å, β=128.647(4)°. Th(CrO4)2(H2O)2 (5), P21/n, a=12.731(1), b=9.469(8), c=12.972(1) Å, β=91.793(2)°. K2Th3(CrO4)7(H2O)10 (6), Ama2, a=19.302(8), b=15.580(6), c=11.318(6) Å. 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.