The reactivity of iridium and rhodium complexes with aryloxides, alkoxides, and carbon monoxide
Abstract
The complexes, (Ir(triphos)($\eta\sp4$-cod)) (Cl), 1, and (Rh(triphos)CO) (PF$\sb6$), 19 both offer insight into the mechanistic requirements for catalytic deoxygenation of phenols with carbon monoxide. The evolution of CO$\sb2$ and arenes (benzene and toluene) were observed when complex 1 is placed in ArOH $\{$Ar = C$\sb6$H$\sb5,$ C$\sb6$H$\sb{5-p-}$CH$\sb3\}$ under an atmosphere of carbon monoxide. The important intermediate, aryloxycarbonyl, is observable by FTIR spectroscopy during the reaction of complex 19 with aryloxides. The mechanism of cyclooctadiene deprotonation of 1 utilizing various bases has been explored. The mechanism followed when weak bases, such as NaOCH$\sb3$, NaOC$\sb6$H$\sb5$, NaOC$\sb6$H$\sb4$-p-CH$\sb3$, or NaOC$\sb6$H$\sb4$-p-C(CH$\sb3$)$\sb3$, are employed involves a Michael type addition followed by elimination of the conjugate acid. While a direct deprotonation mechanism occurred when stronger bases, such as KOH, N(C$\sb2$H$\sb5$)$\sb3$, pyridine, or N,N,N$\sp\prime$,N$\sp\prime$-tetramethyl-1,8-naphthalenediamine (proton sponge), are employed. Both mechanisms result in the formation of (Ir(triphos)(1,2-$\eta\sp2$, 6-$\sigma$-cycloocta-1,4-dienyl), 2. The investigation of nucleophilic attack on the coordinated carbonyls of other rhodium and iridium complexes is also presented.
Degree
Ph.D.
Advisors
Kubiak, Purdue University.
Subject Area
Chemistry
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