Synthesis and Reactivity of Cyclohexadienyl-and o-Xylylenetricarbonylmanganese Complexes Obtained from the Deprotonation of [Mn(η6-arene)(CO)3]+ Salts

John W. Hull, Kevin J. Roesselet, Wayne L Gladfelter

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Abstract

Following deprotonation of [Mn(η6-C6Me6)(CO)3]+ with K(OtBu) to give the known exomethylene cyclohexadienyl complex, a second deprotonation was accomplished using the dual base system K(OtBu)/KH in THF. The product was the anionic o-xylylene complex K{Mn[η4-C6Me4(CH2)2](CO)3}. The cyclohexadienyl complex from a single deprotonation of [Mn(η6-o-xylene)(CO)3]+ was stable only in solution at room temperature, but direct double deprotonation with K(OtBu)/KH gave the anionic o-xylylene complex K{Mn[η4-C6H4(CH2)2] (CO)3} as a thermally stable solid. Deprotonation of [Mn(η6-toluene)(CO)3]+, [Mn-(η6-C6H5Et) (CO)3]+, and [Mn-η6-C6H5-i-Pr)(CO)3]+ salts with excess K(OtBu) gave the isolable cyclohexadienyl complexes [η5-C6H5(CH2)]Mn(CO)3, [η5-C6H5(CHCH3)Mn(CO)3, and [η-C6H5(CMe2)Mn(CO)3, respectively. All deprotonation products were air and moisture sensitive. Reaction of [η5-C6H5(CH2)]Mn(CO)3 with HPF6 and Br2 yielded [Mn(η6-toluene)(CO)3]+ and {Mn[(η6-C6H5(CH2Br)](CO)3)}+, respectively. The anionic o-xylylene complexes gave crystalline solids with ether solvents such as 1,2-dimethoxyethane, diglyme, and dioxane. Mono-and dialkylation of [η5-C6Me5(CH2)]Mn(CO)3 and K{Mn[η4-C6Me4(CH2)2](CO)3} with CF3SO3CH3 gave the [Mn(η6-C6Me5Et)(CO)3]+ and [Mn(η6-1,2-C6Me4Et2)(CO)3]+ salts, respectively. Attempted alkylation of K{Mn[η4-C6H4(CH2)2](CO)3)} in a similar fashion gave unidentified solids. Treatment of the cyclohexdienyl or o-xylylene complexes with molecular oxygen gave only the parent hydrocarbons, hexamethylbenzene or o-xylene, as the isolated organic products.

Original languageEnglish (US)
Pages (from-to)3630-3635
Number of pages6
JournalOrganometallics
Volume11
Issue number11
DOIs
StatePublished - Nov 1 1992

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