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Title:High oxidation state organometallics and their charge transfer materials
Author(s):Morse, David B.
Doctoral Committee Chair(s):Rauchfuss, Thomas B.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Inorganic
Abstract:This research has been directed toward the systematic design and synthesis of highly oxidizing complexes. These complexes have been used as components in the molecular synthesis of solid state materials displaying cooperative electronic interactions. Complexes of the type CpVX$\sb3$ (Cp = $\eta\sp5$-C$\rm\sb5$H$\sb5$ or -$\rm C\sb5H\sb4$Me; X = Cl, Br) are highly oxidizing. The oxidation potential can be tuned by changes in the cyclopentadienyl ligand, halides, or with a strongly $\pi$-bonding oxide. Their electronic ground states were characterized.
Reaction of these organometallic acceptors with the organic donor TmTEF (E = S, Se; tetramethyltetrathio(seleno)fulvalene) formed materials such as (TmTTF) ((MeCp)VCl$\sb3\rbrack$ and (TmTTF$\rbrack\sb3\lbrack\{$MeCp) VCl$\sb2\}\sb2$O$\rbrack\sb2$. The mixed-valence salt of TmTTF and $\{$(MeCp)VCl$\sb2\}\sb2$O$\sp-$ exhibits field dependent magnetic behavior. The single crystal magnetic susceptibility of this one-dimensional solid has defined it as an XY ferromagnet. The low field ferromagnetic response arises from spin alignment within the organometallic fragments. The complex (TmTSF) (CpVBr$\sb3\rbrack\cdot$CH$\sb2$Cl$\sb2$ also displays field dependent properties.
Oxidants such as CpVX$\sb3$ also form partial charge transfer complexes. The organometallic donor Cp$\sb2$Fe forms a complex with CpVBr$\sb3$, which exists as Cp$\sb2$Fe$\sp+$CpVBr$\sb3$- in the solid state. CpVI$\sb3$ forms a charge transfer aggregate in solution wherein one group acts as a donor and another as acceptor. A crystallographic characterization demonstrates vanadium to iodine charge transfer at ambient temperatures, and the vanadium(III) ground state at low temperature.
In the chromium analogs of the CpMX$\rm\sb{n}$ complexes, halogens are unable to oxidize (Cp*CrX$\sb2\rbrack\sb2$ (Cp* = $\eta\sp5$-C$\sb5$Me$\sb5$) complexes to form mononuclear Cp*CrX$\sb3$ species. Dioxygen can be activated though to form Cp*CrOX$\sb2$ compounds. These complexes will catalytically oxidize phosphines (OPR$\sb3$) and organic sulfides (OSR$\sb2$) depending upon the type of Cp-group and X. The oxide may be removed by photolysis, thermolysis, or other means resulting in recovery of up to 75% of the starting material.
The (Cp*CrX$\sb2\rbrack\sb2$ series may reacted with halogens to form charge transfer complexes such as (Cp*CrX$\sb2\rbrack\sb2\cdot$X$\sb2$ (X = Br, I). Both complexes form polymeric solids, but the iodine system displays increased reactivity due to the Lewis acid character of I$\sb2$. "Cp*CrI$\sb3$" is a polymer with a distorted polyiodide linkage forming two different (Cp*Cr-I$\sb2\rbrack\sb2$ environments. The iodides are electron rich in this complex, and the polymer will absorb additional iodine. "Cp*CrI$\sb{5.5}$" has been identified as ((Cp*)$\sb2$Cr$\sb2$I$\sb3\rbrack\sb2\lbrack$I$\sb{16}\rbrack,$ an infinite polyiodide network based on the iodine-rich I$\sb{16}\sp{2-}$.
Issue Date:1989
Rights Information:Copyright 1989 Morse, David B.
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI8924907
OCLC Identifier:(UMI)AAI8924907

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