Photochemical Generation of a Reactive Transition-Metal Fragment. Photochemically Induced Arene Replacement Reactions of the Cyclopentadienyl(p-xylene)Iron(II) Ion

Thomas P. Gill, Kent R. Mann

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111 Scopus citations

Abstract

Visible-light irradiation of FeCp(p-xyl)+ (Cp = cyclopentadienyl, p-xyl = p-xylene) in organic solvents in the presence of suitable ligands leads to the formation of products in which the three coordination sites occupied by p-xylene have been replaced to give complexes of the form FeCpL3 + (L3 = (p-CNPhCH3)3, (CO)3, hexamethylbenzene, and triphos), which have been isolated and characterized as PF6 - or BF4 - salts. The quantum yields for the formation of these products are rather large. For example, irradiation (436 nm) of the LF bands of FeCp(p-xyl)+ in methylene chloride in the presence of 0.05 M triphos (bis(2-(diphenylphosphino)ethyl)phenylphosphine) yields FeCp(triphos)+ with θ = 0.57 ± 0.06. The course of the photochemical reaction was different in methylene chloride solution with 1, 10-phenanthroline added or in aqueous 0.1 NH2SO4 solution. The 436-nm irradiation of FeCp(p-xyl)+ in methylene chloride in the presence of 0.1 M 1, 10-phenanthroline leads to the formation of Fe(phen)32+ with a quantum yield of 0.58 α 0.06. Similarly, 436-nm-irradiation of FeCp(p-xyl)+ in 0.1 N aqueous H2SO4 solution leads to the formation of Fe2+(aq) with a quantum yield of 0.81 α 0.08. The possible mechanisms for these reactions are tentatively discussed in terms of replacement of p-xylene to produce a reactive transition-metal fragment containing the FeCp+ unit, which undergoes addition of incoming ligand L to form complexes of the form FeCpL3 + or FeLn2+.

Original languageEnglish (US)
Pages (from-to)3007-3010
Number of pages4
JournalInorganic Chemistry
Volume19
Issue number10
DOIs
StatePublished - Jan 1 1980

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