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Title:I. An oxygen-17 NMR study on oxygen exchange in yttrium barium(2) copper(3) oxygen(7-x). II. Synthesis of transition metal polysulfide complexes from metal powders
Author(s):Ramli, Emannuel
Doctoral Committee Chair(s):Rauchfuss, Thomas B.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Inorganic
Abstract:Covellite, $\rm Cu\sp{I}\sb2(S\sb2)Cu\sp{II}S$ (T$\sb{\rm c}$ = 1.66 K) and $\rm YBa\sb2Cu\sp{II}\sb2Cu\sp{III}O\sb{7-x}\ (T\sb{c}$ = 92 K) are similar in that both are superconductors containing layered structures and mixed valent copper centers. Our studies on YBa$\sb2$Cu$\sb3$O$\sb{\rm 7-x}$ focused on $\sp{17}$O-labelling of samples of $\rm YBa\sb2 Cu\sb3 O\sb{7-x}$ and the $\sp{17}$O NMR studies of these samples. The $\sp{17}$O-labelling process was carried out using a specially designed glass apparatus. Powder X-ray diffraction and magnetic susceptibility measurements showed that our samples were highly pure. $\sp{17}$O NMR spectroscopy showed that we were able to prepare samples which have uniform and non-uniform distribution of $\sp{17}$O atoms.
Our work on covellite began with studies of its synthesis at low temperatures. This work led to the discovery of a low temperature route to metal sulfides. We initially prepared covellite by the reaction of a suspension of copper metal and elemental sulfur in refluxing pyridine. When the same reaction was conducted at room temperature we obtained amorphous CuS and (Cu(S$\sb5$)$\sb2$(pyridine)) $\sb4$. (Cu(S$\sb5)\sb2$(pyridine)) $\sb4$ was shown to be a molecular intermediate in the formation of covellite from its elements. Subsequently it was found that the reaction between copper and sulfur is particularly rapid in N-methylimidazole, affording (Cu(S$\sb5$)$\sb2$(N-MeIm)) $\sb4$ in 50% yield.
Other first row transition metals which react with S$\sb8$ in N-methylimidazole at room temperature include manganese, iron and nickel. The product in all of these cases is (M(N-MeIm)$\sb6$) S$\sb8$ (M = Mn, Fe, Ni). (M(N-MeIm)$\sb6$) S$\sb8$ provides the first evidence for S$\sb8\sp{2-}$ anion, the product of the 2 e$\sp-$ reduction of S$\sb8$.
Zinc metal reacts with S$\sb8$ in N-methylimidazole at 90$\sp\circ$C to form (ZnS(N-MeIm)) $\sb{\rm n}$ when Zn: S = 1: 1 and ZnS$\sb6$(N-MeIm)$\sb2$ when Zn: S = 1: 6. The two compounds are interconvertible via addition of elemental sulfur or zinc.
Issue Date:1991
Rights Information:Copyright 1991 Ramli, Emannuel
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9124471
OCLC Identifier:(UMI)AAI9124471

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