7789-52-8Relevant articles and documents
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.
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.
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.
