7789-52-8Relevant academic research and scientific papers
A simple method for the preparation of selenopheno[3,2-b] and [2,3-b]thiophenes
Arsenyan, Pavel
, p. 2527 - 2529 (2014/05/06)
A simple strategy for the preparation of novel selenopheno[3,2-b] and [2,3-b]thiophenes by treatment of ethynylthiophenes with selenium(I), (II), and (IV) chlorides and bromides is elaborated.
Stereoselective synthesis of (E,E)-bis(2-halovinyl) selenides and its derivatives based on selenium halides and acetylene
Musalov, Maxim V.,Potapov, Vladimir A.,Musalova, Maria V.,Amosova, Svetlana V.
, p. 10567 - 10572,6 (2012/12/12)
Efficient stereoselective synthesis of (E,E)-bis(2-chlorovinyl) and (E,E)-bis(2-bromovinyl) selenides in 95-98% yield based on the reactions of selenium dihalides or monohalides with acetylene has been elaborated. Reactions of selenium tetrahalides with a
Metastable Se6 as a ligand for Ag+: From isolated molecular to polymeric 1D and 2D structures
Aris, Damian,Beck, Johannes,Decken, Andreas,Dionne, Isabelle,Schmedt Auf Der Guenne, Joern,Hoffbauer, Wilfried,Koechner, Tobias,Krossing, Ingo,Passmore, Jack,Rivard, Eric,Steden, Folker,Wang, Xinping
, p. 5865 - 5880 (2011/07/31)
Attempts to prepare the hitherto unknown Se62+ cation by the reaction of elemental selenium and Ag[A] ([A]- = [Sb(OTeF5)6]-, [Al(OC(CF3) 3)4]-) in SO2 led to the formation of [(OSO)Ag(Se6)Ag(OSO)][Sb(OTeF5)6] 21 and [(OSO)2Ag(Se6)Ag(OSO) 2][Al(OC(CF3)3)4]22a. 1 could only be prepared by using bromine as co-oxidant, however, bulk 2b (2a with loss of SO2) was accessible from Ag[Al(OC(CF3) 3)4] and grey Se in SO2 (chem. analysis). The reactions of Ag[MF6] (M = As, Sb) and elemental selenium led to crystals of 1/∞{[Ag(Se6)]∞[Ag 2(SbF6)3]∞} 3 and {1/∞[Ag(Se6)Ag]∞}[AsF6] 24. Pure bulk 4 was best prepared by the reaction of Se 4[AsF6]2, silver metal and elemental selenium. Attempts to prepare bulk 1 and 3 were unsuccessful. 1-4 were characterized by single-crystal X-ray structure determinations, 2b and 4 additionally by chemical analysis and 4 also by X-ray powder diffraction, FT-Raman and FT-IR spectroscopy. Application of the PRESTO III sequence allowed for the first time 109Ag MAS NMR investigations of 4 as well as AgF, AgF2, AgMF6 and {1/∞[Ag(I2)]∞}[MF 6] (M = As, Sb). Compounds 1 and 2a/b, with the very large counter ions, contain isolated [Ag(Se6)Ag]2+ heterocubane units consisting of a Se6 molecule bicapped by two silver cations (local D3d sym). 3 and 4, with the smaller anions, contain close packed stacked arrays of Se6 rings with Ag+ residing in octahedral holes. Each Ag+ ion coordinates to three selenium atoms of each adjacent Se6 ring. 4 contains [Ag(Se6) +]∞ stacks additionally linked by Ag(2)+ into a two dimensional network. 3 features a remarkable 3-dimensional [Ag 2(SbF6)3]- anion held together by strong Sb-F...Ag contacts between the component Ag+ and [SbF6]- ions. The hexagonal channels formed by the [Ag2(SbF6)3]- anions are filled by stacks of [Ag(Se6)+]∞ cations. Overall 1-4 are new members of the rare class of metal complexes of neutral main group elemental clusters, in which the main group element is positively polarized due to coordination to a metal ion. Notably, 1 to 4 include the commonly metastable Se6 molecule as a ligand. The structure, bonding and thermodynamics of 1 to 4 were investigated with the help of quantum chemical calculations (PBE0/TZVPP and (RI-)MP2/TZVPP, in part including COSMO solvation) and Born-Fajans-Haber-cycle calculations. From an analysis of all the available data it appears that the formation of the usually metastable Se6 molecule from grey selenium is thermodynamically driven by the coordination to the Ag+ ions.
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.
Exchange processes in diselenium and selenium-sulfur dihalides, Se2X2 and SeSX2 (X = Br, Cl). A 77Se 2D-EXSY study
Milne, John,Williams, Antony J.
, p. 4534 - 4538 (2008/10/08)
The application of two-dimensional NMR exchange spectroscopy (2D-EXSY) to the study of 77Se exchange kinetics in mixtures of S2Cl2 and Se2Br2, which contain disulfur, diselenium, and selenium sulfur dihalides, shows that 77Se magnetization transfer takes place predominantly by an exchange process, in which only SeX bonds are broken. Direct exchange via mechanisms, involving ChX radicals, four-chalcogen center transition states and mono- and trichalcogen dihalide species are not consistent with the cross peaks observed in the 2D spectra. Magnetization transfer by means of a bimolecular halogen-bridged intermediate (Chemical Equation Presented) or by an ionic process, involving Se-X bonds, are both consistent with the pattern of cross observed. However, the addition of tetraethylammonium chloride to the S2Cl2/Se2Br2 mixture causes the eight-signal spectrum to collapse to three broad signals, which favors an interpretation in terms of an ionic exchange mechanism. The three broad signals are assigned to BrSSeX, ClSSeX, and SeSe dihalides each undergoing rapid ionic exchange, involving SeX bonds.
Intra- and intermolecular correlations in liquid selenium-halogen systems
Maruyama, Kenji,Kawakita, Yukinobu,Yao, Makoto,Endo, Hirohisa,Misawa, Masakatsu
, p. 3032 - 3044 (2008/10/08)
The structure of liquid (1-) selenium-halogen mixtures has been studied by both EXAFS and neutron scattering measurements. The concentration variation of the coordination numbers of Se and halogen atoms around the central Se atom were determined. It was f
The nature of selenium dissolved in hydrobromic acid containing selenium dioxide
Milne, John
, p. 1056 - 1060 (2007/10/02)
Elemental selenium dissolves in solutions of selenium dioxide in hydrobromic acid.In 8.72M HBr, there is complete reaction to give Se2Br2 and SeBr42- as shown by solubility studies and Raman spectroscopy.When the Se2Br2 concentration exceeds 0.0116M, insoluble Se2Br2 is formed.The equilibrium constant for the reaction, Se2Br2 + 2Br- = SeBr42- + Se has been determined, K=0.025(+/-0.002) mol-2L2.Solutions of SeO2 and Se in 4.8M HBr contain Se(IV), Se(II), and Se(I) in equilibrium, 3SeBr42- + H2O = Se2Br2 + SeOBr3- + 7Br- + 2H+.The equilibrium constant for this reaction is 10.0(+/-0.7)x1012 mol8L-8.The solubility of Se2Br2 at saturation in 4.8M HBr is 0.0052M.Key words: selenium bromides, bromoselenates, hydrobromic acid, solution equilibria, solubility.
Crystal Structures of Compounds A2X2 (A = S, Se; X = Cl, Br)
Kniep, Ruediger,Korte, Lutz,Mootz, Dietrich
, p. 1 - 6 (2007/10/02)
The crystal structures of compounds A2X2 (A = S, Se; X = Cl, Br) contain molecules X-A-A-X with dihedral angles between 83.9 deg and 87.4 deg.Three different types of molecular packing are realized: S2Cl2, S2Br2 (α-Se2Br2) and β-Se2Br2(Se2Cl2).Details of molecular geometries as well as crystal structures are discussed. - Keywords: Sulfur(I) Halides, Selenium(I) Halides, Crystal Structure
