Alkoxy-alkylcarbene complexes [OsCl{=C(OR′)CH 2R′′}(η6-p-cymene)L]BPh4 (1-4) [R′ = Me, Et; R′′ = Ph, p-tolyl, But; L = P(OMe)3, P(OEt)3, PPh(OEt)2, PPh 2OEt] were prepared by allowing dichloro compounds OsCl 2(η6-p-cymene)L to react with terminal alkyne R′′C=CH in alcohol. Ethoxy-methylcarbene [OsCl{=C(OEt)CH 3}(η6-p-cymene)L]BPh4 (5) was also prepared from reaction with trimethylsilyl acetylene. A reaction path for the formation of compounds 1-5, involving the nucleophilic attack of alcohol on intermediate vinylidene complexes, is discussed. Acetylide derivatives OsCl(C=CAr) (η6-p-cymene)L (6, 7) [Ar = Ph, p-tolyl; L = P(OMe)3, P(OEt)3, PPh(OEt)2] were prepared by reacting dichloro compounds OsCl2(η6-p-cymene)L with lithium acetylide (Li+[ArC=C]-) in thf. Protonation reaction with Brønsted acids of 6 and 7 led to vinylidene cations [OsCl{=C=C(H)Ar} (η6-p-cymene)L]+. Complexes OsCl2(η 6-p-cymene)L also reacted with both PhC=CH and (CH3) 3SiC=CH in the presence of H2O to give alkyl-carbonyl derivatives [Os(η1-CH2Ph)(CO)(η6-p- cymene)L]BPh4 (8) and [Os(η1-CH3)(CO) (η6-p-cymene)L]BPh4 (9). The complexes were characterized spectroscopically (IR and 1H, 13C, 31P NMR) and by X-ray crystal structure determinations of [OsCl{=C(OEt)CH2Ph}(η6-p-cymene){PPh(OEt) 2}]BPh4 (1c), [OsCl{=C(OEt)CH2Ph} (η6-p-cymene)(PPh2OEt)]BPh4 (1d), and [Os(η1-CH2Ph)(CO)(η6-p-cymene){PPh(OEt) 2}]BPh4 (8c). © 2011 American Chemical Society.
Preparation of Half-sandwich Alkoxycarbene Complexes of Osmium(II)
ALBERTIN, Gabriele;ANTONIUTTI, Stefano;
2011-01-01
Abstract
Alkoxy-alkylcarbene complexes [OsCl{=C(OR′)CH 2R′′}(η6-p-cymene)L]BPh4 (1-4) [R′ = Me, Et; R′′ = Ph, p-tolyl, But; L = P(OMe)3, P(OEt)3, PPh(OEt)2, PPh 2OEt] were prepared by allowing dichloro compounds OsCl 2(η6-p-cymene)L to react with terminal alkyne R′′C=CH in alcohol. Ethoxy-methylcarbene [OsCl{=C(OEt)CH 3}(η6-p-cymene)L]BPh4 (5) was also prepared from reaction with trimethylsilyl acetylene. A reaction path for the formation of compounds 1-5, involving the nucleophilic attack of alcohol on intermediate vinylidene complexes, is discussed. Acetylide derivatives OsCl(C=CAr) (η6-p-cymene)L (6, 7) [Ar = Ph, p-tolyl; L = P(OMe)3, P(OEt)3, PPh(OEt)2] were prepared by reacting dichloro compounds OsCl2(η6-p-cymene)L with lithium acetylide (Li+[ArC=C]-) in thf. Protonation reaction with Brønsted acids of 6 and 7 led to vinylidene cations [OsCl{=C=C(H)Ar} (η6-p-cymene)L]+. Complexes OsCl2(η 6-p-cymene)L also reacted with both PhC=CH and (CH3) 3SiC=CH in the presence of H2O to give alkyl-carbonyl derivatives [Os(η1-CH2Ph)(CO)(η6-p- cymene)L]BPh4 (8) and [Os(η1-CH3)(CO) (η6-p-cymene)L]BPh4 (9). The complexes were characterized spectroscopically (IR and 1H, 13C, 31P NMR) and by X-ray crystal structure determinations of [OsCl{=C(OEt)CH2Ph}(η6-p-cymene){PPh(OEt) 2}]BPh4 (1c), [OsCl{=C(OEt)CH2Ph} (η6-p-cymene)(PPh2OEt)]BPh4 (1d), and [Os(η1-CH2Ph)(CO)(η6-p-cymene){PPh(OEt) 2}]BPh4 (8c). © 2011 American Chemical Society.File | Dimensione | Formato | |
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