343. The crystal structures of ThSe2 and Th7Se12

Abstract

By R. W. M. D'EYE.The crystal structures of ThSe, and Th,Se,, have been determined from powder photographs obtained by use of Guinier-type focusing cameras. ThSe, is orthorhombic with a = 4.411 & 0-002 kX, b = 7-595 5 0-002 kX, c = 9.046 f 0-002 kX. There are 4 molecules per unit cell and the space-group is Diz-Pmnb. Th,Se,, is hexagonal with a = 11-546 j--0.006 k X c = 4-22 f 0.01 k X . There is one molecule per unit cell and the space-group is CZh-PS3/m. Both compounds are thus isostructural with their corresponding sulphides.IN a recent report (D'Eye, Sellman, and Murray, J., 1952, 2555) of an investigation of the Th-Se system the compounds ThSe, and Th,Se,, were described. However, owing to the poor powder-diffraction data obtained from Debye-Schemer photographs it was then not possible to determine unambiguously the crystal structures of these two compounds. Through the courtesy of Professor G. Hagg in allowing me to work at his Institute in Uppsala University, Sweden, it has been possible to obtain good diffraction data by use of Guinier-type focusing cameras which necessarily eliminate the spacing errors caused by absorption in the specimen. It was tentatively suggested in the previous communication that Th,Se,, and ThSe, had hexagonal and orthorhombic lattices, respectively, and that they were isostructural with their corresponding sulphides. This has now been established. EXPERIMENTAL X-Ray photographs were obtained by using Guinier-type focusing cameras with a bent quartz-crystal monochromator and Cu-Ka radiation. The intensities of the resulting diffraction lines were visually estimated. The expression for the intensity of a diffraction line on a Guiniertype photograph is I,ocA ,A2pF2 ( 1 + c 0 s ~2 8 ~ cos2 28)/sin28 cos8, where I,, 8, Om, A A,, p , and

Use of77Se and125Te NMR Spectroscopy to Probe Covalency of the Actinide-Chalcogen Bonding in [Th(En){N(SiMe3)2}3]−(E = Se, Te;n= 1, 2) and Their Oxo-Uranium(VI) Congeners

“…Complexes 2 and 3 both crystallize in the triclinic space group P1̅ as diethyl ether solvates, 2• 0.5Et 2 O and 3•0.5Et 2 O, and their solid-state molecular structures are shown in Figure 1 (see also Table 1 5b For further comparison, the average Th− Se distance in ThSe 2 is 3.06 Å (with d(Th−Se) ranging from 2.85 to 3.27 Å). 16 The Th−Te distances of 3 (Th1−Te1 = 3.1076(4) and Th1−Te2 = 3.2375(4) Å) are longer than the Th−Se bond distances of 2, consistent with the larger ionic radii of Te 2− versus Se 2− . 17 While no other coordination complexes with Th−Te bonds have been reported, 8 several solid-state thorium tellurides are known, including KTh 2 Te 6 , 18 ThTe 2 I 2 , 19 and Th 7 Te 12 .…”

“…The Th–Se distances in 2 (Th–Se = 2.8750(7) and 2.9555(7) Å) are comparable to previously reported Th–Se single bonds. ,, For example, the average Th–Se bond length in [Th­(Se 2 P­(C 6 H 5 )­(OMe)) 4 ] is 3.027 Å, while the average Th–Se bond length in [(η 5 -1,3-(Me 3 C) 2 C 5 H 3 ) 2 Th­(SePh) 2 ] is 2.88 Å . For further comparison, the average Th–Se distance in ThSe 2 is 3.06 Å (with d­(Th–Se) ranging from 2.85 to 3.27 Å) . The Th–Te distances of 3 (Th1–Te1 = 3.1076(4) and Th1–Te2 = 3.2375(4) Å) are longer than the Th–Se bond distances of 2 , consistent with the larger ionic radii of Te 2– versus Se 2– .…”

Molecular Thorium Compounds with Dichalcogenide Ligands: Synthesis, Structure, 77Se NMR Study, and Thermolysis

“…Thermolysis of 4 was performed under the same conditions as previously reported for (py) 3 Th­(SePh) 4 . The PXRD analysis revealed that ThSe 2 is the only solid-state product, with no evidence for the formation of any ternary ThISe phases. The surface morphology of the resulting powder of the thermal residual is shown in Figure by SEM, and this ThSe 2 stoichiometry was also confirmed by EDS (Figure S25), with trace (<3%) iodide present.…”

An Alphabetical Index of Work on Metals and Alloys

“…Se 12 Th 7 has a hexagonal unit cell, isomorphous with Th 7 S 12 , a = 11-546 ± 6, c = 4-22 ± 1 kX, D x = 8-7 g/cm 3 , M = 1, P6 3 //n (D'EYE, 1953). The approximate atom positions and parameters were determined from powder photographs taken in a Guinier type of focusing camera.…”