Photochemistry of [(η-C5H5)Fe(η-p-xyl)]PF6 in Acetonitrile Solution. Characterization and Reactivity of [(η-C5H5)Fe(CH3CN)3]+

Thomas P. Gill, Kent R Mann

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Abstract

The photolysis of [(η-C5H5)Fe(η-p-xyl)]+ (xyl = xylene) in acetonitrile solution at -40 °C produces a purple intermediate that we have characterized as [(η-C5H5)Fe(CH3CN)3]+ by 1H NMR, electronic spectroscopy, and chemical reaction studies. Room-temperature photolysis of [(η-C5H5)Fe(η-p-xyl)]+ in acetonitrile also generates this species, which rapidly yields ferrocene and Fe(II) as the final products. Mechanistic studies on this system suggest that ferrocene is generated when [(η-C5H5)Fe(CH3CN)3]+ releases C5H5 -, which subsequently replaces three CH3CN molecules on an unreacted [(η-C5H5)Fe(CH3CN)3]+ ion. This tris(acetonitrile) complex is a convenient starting material for the synthesis of substituted complexes of the form [(η-C5H5)Fe(CH3CN)(L)2]+, [(η-C5H5)Fe(CH3CN)(L)(L′)]+, [η-C5H5)Fe(L)(L′)2]+, and [(η-C5H5)Fe(L)(L′)(L”)]+, where L, L′, and L” = isocyanides, phosphites, or phosphines. Room-temperature photolysis of [(η-C5H5)Fe(η-p-xyl)]+ in CH3CN in the presence of excess L produces [η-C5H5)Fe(CH3CN)(L)2]+. Photolysis at -40 °C in CH3CN, followed by the addition of 1 equiv of L and a warm-up step in the presence of excess L′, produces [(η-C5H5)Fe(CH3CN))L)(L′)]+. The reaction of the disubstituted compounds with excess ligand produces complexes of the form [η-C5H5)Fe(L′)(L)2]+ and [(η-C5H5)Fe(L)(L′)(L″)], respectively. Reactivity comparisons of [(η-C5H5)Fe-(CH3CN)n (L)3-n] and [(η-C5H5)Ru(CH3CN)n(L)3-n] (n ≠ 0) have also been made. In every case the Fe complex has been found to undergo substitution reactions more readily than the corresponding Ru analogue.

Original languageEnglish (US)
Pages (from-to)1986-1991
Number of pages6
JournalInorganic Chemistry
Volume22
Issue number14
DOIs
StatePublished - Jul 1983

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