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|Title:||Sulfur Rich Transition Metal-Main Group Heterocycles and Cages|
|Author(s):||Zank, Gregg A.|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The reactivity of elemental sulfur homocycles has long been postulated to occur via highly reactive thiopolysulfide (S=S) ring intermediates. Consistent with the reactivity associated with these postulated S=S intermediates is that observed for the organoperthiophosphinic acid anhydrides, R(,2)P(,2)S(,4), 1. These anhydrides are one of the most efficient reagents known for the thiation of organic carbonyl compounds.
In an effort to enhance the reactivity of the well studied Cp(,2)TiS(,5) system we sought to incorporate RP(S) fragments into the pentasulfide ring. These metal complexes of these phosphorus sulfide chelates were found to have a similar reactivity toward organic substrates as 1, but unlike 1 reacted readily with dioxygen. The investigation into the reactivity of these transition metal complexes has lead to a better understanding of the reactivity of the parent R(,2)P(,2)S(,4) anhydrides themselves. A kinetics study of the sulfur transfer reactivity of 1 indicated RPS(,2) fragments as the reactive species.
Replacement of the organic group of these organothiophosphoryl (RPS(,2)) ligands with sulfide affords, formally, condended anions of the trithiophosphite (PS(,3)('2-)). Divalent metal salts of these dianions (MTS(,3), T = P, As) have been employed as intercalation hosts, while mono- and divalent metal salts of the TS(,3)('3-) trianion form a large class of minerals termed Sulfosalts. The minerals Orpiment (As(,2)S(,3)) and Realgar (As(,4)S(,4)) were found to dissolve in the presence of sulfide which followed by metathesis with organotransition metal halides or through the use of nucleophilic transition metal sulfides has lead to the isolation of molecular sulfosalts.
One of these molecular Sulfosalts (Cp(,3)Ti(,2)OAsS(,3)) structurally resembles the T(,4)S(,3) (T = P, As) cages. This observation suggested the possibility of preparing (CpTi)(,4)S(,x) cages. The two isolated complexes from this reaction were Cp(,4)Ti(,4)S(,8)O(,x) (x = 1,2) which like the E(,4)S(,x) cages are comprised of a tetrahedral array of trivalent atoms. Unlike the main group cages these Ti(,4) compounds contained (mu)(,4)-oxides and bridging disulfides.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
|Date Available in IDEALS:||2014-12-15|