Mercury(II) complexes with l-cysteine (H(2)Cys) in alkaline aqueous solutions have been structurally characterized by means of extended X-ray absorption fine structure (EXAFS) spectroscopy. The distribution of [Hg(Cys)(n)] (n = 2, 3, and 4) species in approximately 0.09 mol dm(-3) mercury(II) solutions with H(2)Cys/Hg(II) ratios varying from 2.2 to 10.1 has been evaluated by fitting linear combinations of simulated EXAFS functions for the separate complexes to the experimental EXAFS data, aided by (199)Hg NMR and Raman results. For the [Hg(Cys)(2)](2-) and [Hg(Cys)(3)](4-) complexes and the novel four-coordinated Hg(Cys)(4) species that dominates in solutions with excess of cysteine (H(2)Cys/Hg(II) > 5), the mean Hg-S bond distances were found to be 2.35(2), 2.44(2), and 2.52(2) Angstroms, respectively. The minor amount of the linear [Hg(Cys)(2)](2-) complex that can still be discerned in solutions with ratios up to H(2)Cys/Hg(II) = 5 was derived from the distinct S-Hg-S symmetric stretching Raman band at 334 cm(-1). From (199)Hg NMR spectra, the chemical shift of the Hg(Cys)(4) species was estimated to -340 ppm with an amount exceeding 85% in the highest excess of cysteine, consistent with the EXAFS data.
In marine-archaeological oak timbers of the Mary Rose large amounts of reduced sulfur compounds abound in lignin-rich parts such as the middle lamella between the cell walls, mostly as thiols and disulfides, whereas iron sulfides and elemental sulfur occur in separate particles. Synchrotron-based x-ray microspectroscopy was used to reveal this environmentally significant accumulation of organosulfur compounds in waterlogged wood. The total concentration of sulfur in reduced forms is Ϸ1 mass % throughout the timbers, whereas iron fluctuates up to several mass %. Conservation methods are being developed aiming to control acid-forming oxidation processes by removing the reactive iron sulfides and stabilizing the organosulfur compounds.organosulfur ͉ waterlogged wood ͉ iron sulfides ͉ conservation ͉ marine archaeology
Sodium trichloromethanesulfonate monohydrate, Na+.CCl3SO3-.H2O, crystallizes in P2(1)/a with all the atoms located in general positions. The trichloromethanesulfonate (trichlate) anion consists of pyramidal SO3 and CCl3 groups connected via an S-C bond in a staggered conformation with approximate C3v symmetry. The water molecule is hydrogen bonded to the sulfonate O atoms, with one water H atom forming weak bifurcated O-H...O hydrogen bonds to two different trichlate ions. Two water O atoms and three O atoms from different SO3 groups form a square-pyramidal arrangement around the sodium ion.
The sulfur K-edge X-ray absorption near edge spectra (XANES) of the hexakis(dimethyl sulfoxide) solvated trivalent group 13 ions, Al, Ga, In and Tl, in the solid state show larger splitting and different intensity distribution of the main sulfur 1s electronic excitations than for the uncoordinated dimethyl sulfoxide molecule. The transitions have been interpreted by density functional calculations, and the increased splitting is shown to be an effect of metal-oxygen orbital interactions in the bonds to the oxygen coordinated dimethyl sulfoxide ligand.
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