75926-21-5Relevant articles and documents
Syntheses of THF solutions of SeX2 (X = Cl, Br) and a new route to selenium sulfides SenS8-n (n = 1-5): X-ray Crystal Structures of SeCl2(tht)2 and SeCl2·tmtu
Maaninen, Arto,Chivers, Tristram,Parvez, Masood,Pietikaeinen, Jarkko,Laitinen, Risto S.
, p. 4093 - 4097 (2008/10/08)
A simple and efficient synthesis of solutions of pure SeCl2 in THF or dioxane (ca. 0.4 M) at 23 °C was achieved by treatment of elemental selenium with an equimolar amount of SO2Cl2. SeCl2 was characterized by 77Se NMR and Raman spectra. SeCl2 forms 1:1 or 1:2 adducts with tetramethylthiourea (tmtu) or tetrahydrothiophene (tht), respectively. The crystal structure of SeCl2·tmtu (1) reveals a T-shaped geometry [d(Se-Cl) = 2.443(4) A] with weak intramolecular Se-Cl interactions [d(Se-Cl) = 3.276(4) A]. Crystals of 1 are triclinic, space group P1, with a = 8.473(3) A, b = 9.236(3) A, c = 7.709(4) A, α = 109.90(3)°, β= 92.26(4)°, γ = 107.89(3)°, V = 532.9(4) A 3, and Z =2. The complex SeCl2(tht)2 (2) adopts a square planar geometry with d(Se-Cl) = 2.4149-(8) A. Crystals of 2 are monoclinic, space group C2/c, with a - 15.6784(8) A, b = 9.1678(4) A, c = 9.1246(4) A, β= 110.892(2)°, V = 1225.3(1) A,3 and Z = 4. The reaction of Ph3PS with SeCl2 gives Ph3PCl2 and a complex mixture of selenium Sulfides SenS8-n (n = 1-5), which were identified by 77Se NMR. Halogen exchange between SeCl2 and Me3SiBr in THF yields thermally unstable SeBr2 (ca. 0.4 M) characterized by 77Se NMR and Raman spectra.
77Se NMR spectroscopic study of the molecular composition of sulfur-selenium melts
Chivers, Tristram,Laitinen, Risto S.,Schmidt, Kenneth J.
, p. 719 - 725 (2007/10/02)
A series of six sulfur-selenium mixtures containing 0.4, 5, 15, 25, 35, and 45 molpercent of selenium were heated in evacuated ampoules at 430 deg C for 4 h and, keeping the material molten at 135 deg C, their natural-abundance 77Se NMR spectra were recorded.The equilibrium melt in each case was found to contain both heterocyclic SenS8-n species and polymeric material.The most abundant eight-membered selenium sulfide rings were SeS7, which was the main cyclic component in all melts studied in this work, and 1,2-Se2S6, the quantity of which increased with increasing selenium content of the melt.In addition the melts contained smaller amounts of 1,3, 1,4, and 1,5 isomers of Se2S6, 1,2,3, 1,2,4, and 1,2,5 isomers of Se3S5, 1,2,3,4, 1,2,3,5, and 1,2,5,6 isomers of Se4S4, 1,2,3,4,5-Se5S3, 1,2,3,4,5,6-Se6S2, and Se8.The relative distribution of the cyclic products as a function of the selenium content in the melt was virtually identical with that obtained earlier in the CS2 solutions of the quenched melts, implying that the extracted quenched melts actually represent the original melt composition as far as the SenS8-n species are concerned.The resonances due to the polymeric material in the melts could best be interpreted by the statistical random distribution of selenium and sulfur in the polymeric chains, the probability of occurrence of the different fragments being governed by the overall composition of the melt.As the selenium content increases, the relative amount of selenium bound in the polymer seems to increase at the expense of heterocyclic selenium sulfides.Key words: selenium sulfides; sulfur-selenium melt, 77Se NMR spectroscopy.
77Se NMR spectroscopic characterization of selenium sulfide ring molecules SenS8-n
Laitinen, Risto S.,Pakkanen, Tapani A.
, p. 2598 - 2603 (2008/10/08)
77Se NMR spectroscopy has been applied to the study of heterocyclic selenium sulfides SenS8-n obtained from the molten mixtures of the elements with up to 50 mol % selenium. The assignment of the spectra was based on the combined information from the spectra of the natural-abundance samples and from those of the corresponding 77Se-enriched samples. The main selenium-containing components in these mixtures were SeS7 and 1,2-Se2S6 with smaller amounts of 1,3-, 1,4-, and 1,5-isomers of Se2S6, 1,2,3-, 1,2,4-, and 1,2,5-isomers of Se3S5, 1,2,3,4-, 1,2,3,5-, 1,2,4,5-, and 1,2,5,6-isomers of Se4S4, the 1,2,3-isomer of Se5S3, and Se8. In addition, Se6, which is in equilibrium with Se8, could be observed in some samples. The most abundant species within the given isomeric series were those having all selenium atoms adjacent to each other. The trends in the chemical shifts and in the 77Se-77Se coupling constants are presented, and the composition of the phases as a function of the initial melt composition is discussed.
