University of Illinois Urbana-Champaign

Synthesis and Reactivity of Polysulfido Metal Complexes

Pafford, Robert Joseph, IV

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Description

Title
Synthesis and Reactivity of Polysulfido Metal Complexes
Author(s)
Pafford, Robert Joseph, IV
Issue Date
2000
Doctoral Committee Chair(s)
Rauchfuss, Thomas B.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Inorganic
Language
eng
Abstract
The final area of thesis research is the investigation iridium polysulfido complexes. Desulfurization of (NBun4 )Ir(S6)3 with excess PPh3 yields a 30 e-- dimer Ir2S2(PPh4) 4. Crystallographic analysis of Ir2S2(PPh 4)4 reveals a bitetrahedral structure with a pair of mu-S atoms. Two equiv of H2 add to Ir2S2(PPh 4)4 to yield Ir2S(SH)H3(PPh3) 4. The first addition of H2 to Ir2S2(PPh 4)4 proceeds homolytically while the second addition proceeds formally heterolytically. One equiv of H2 adds to Ir2S 2(PPh4)4 to yield Ir2S2H 2(PPh3)4. Low temperature H2 addition to Ir2S2(PPh4)4 reveals an intermediate. This intermediate is a kinetic isomer of compound Ir2S(SH)H 3(PPh3)4. The conversion of this intermediate to Ir2S(SH)H3(PPh3)4 is a first-order reaction with an approximate rate constant of 5 x 10-5 s-1 at -20°C. With a 50 fold excess of H2, the production of Ir2S(SH)H3(PPh 3)4 by the addition of H2 to Ir2S 2H2(PPh3)4 is also a first-order reaction with an approximate rate constant of 3 x 10-5 s -1.
Graduation Semester
2000
Type of Resource
text
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