The reactivity of [Re(CO)5Cl] and [Re2(CO)10] with nucleophiles such as Me3SiO- and MeO- has been investigated by low temperature NMR and by infrared spectroscopy particularly aimed at detecting the [Re(CO)5OR] species, which so far eluded isolation, proposed as intermediates in the synthesis of the dimeric species [Re2(CO)6(-OR)3]- (R = SiMe3, Me). For both nucleophiles the first step involves an interaction with one specific carbonyl ligand and formation of new anionic complexes carrying a metal carboxy silyl or methyl ester, such as cis-[Re(CO)4(COOSiMe3)Cl]-, cis-[Re(CO)4(COOMe)Cl]-, [Re2(CO)9(COOSiMe3)]- and [Re2(CO)9(COOMe)]-. The Re(I) complexes, stable only at low temperature, by further nucleophilic attack generate the well known dimeric [Re2(CO)6(-OR)3]- complexes. The Re(0) metal carboxy-methyl esters derived from [Re2(CO)10] are thermally more stable and can be isolated in the solid state. In particular the new complex [Re2(CO)9(COOMe)][NBu4] has been fully characterized by X-ray diffraction. On the contrary, when the nucleophilic attack involves a weaker OR- nucleophile like [(c-C6H11)7Si8O12O]- or a Re(I) pentacarbonyl substrate which bears a better leaving group such as the triflate, the low temperature nucleophilic attack on a specific carbonyl ligand does not occur.

Low-Temperature Nucleophilic Attack of Me3SiO- and MeO- on Rhenium(I) and Rhenium(0) Carbonyl Complexes / E. Lucenti, G. D’Alfonso, C. Dragonetti, D.M. Roberto, A. Sironi, R. Ugo. - In: ORGANOMETALLICS. - ISSN 0276-7333. - 28:10(2009), pp. 3040-3048.

Low-Temperature Nucleophilic Attack of Me3SiO- and MeO- on Rhenium(I) and Rhenium(0) Carbonyl Complexes

E. Lucenti
Primo
;
G. D’Alfonso
Secondo
;
C. Dragonetti;D.M. Roberto;A. Sironi
Penultimo
;
R. Ugo
Ultimo
2009

Abstract

The reactivity of [Re(CO)5Cl] and [Re2(CO)10] with nucleophiles such as Me3SiO- and MeO- has been investigated by low temperature NMR and by infrared spectroscopy particularly aimed at detecting the [Re(CO)5OR] species, which so far eluded isolation, proposed as intermediates in the synthesis of the dimeric species [Re2(CO)6(-OR)3]- (R = SiMe3, Me). For both nucleophiles the first step involves an interaction with one specific carbonyl ligand and formation of new anionic complexes carrying a metal carboxy silyl or methyl ester, such as cis-[Re(CO)4(COOSiMe3)Cl]-, cis-[Re(CO)4(COOMe)Cl]-, [Re2(CO)9(COOSiMe3)]- and [Re2(CO)9(COOMe)]-. The Re(I) complexes, stable only at low temperature, by further nucleophilic attack generate the well known dimeric [Re2(CO)6(-OR)3]- complexes. The Re(0) metal carboxy-methyl esters derived from [Re2(CO)10] are thermally more stable and can be isolated in the solid state. In particular the new complex [Re2(CO)9(COOMe)][NBu4] has been fully characterized by X-ray diffraction. On the contrary, when the nucleophilic attack involves a weaker OR- nucleophile like [(c-C6H11)7Si8O12O]- or a Re(I) pentacarbonyl substrate which bears a better leaving group such as the triflate, the low temperature nucleophilic attack on a specific carbonyl ligand does not occur.
Settore CHIM/03 - Chimica Generale e Inorganica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/67028
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