The reactivity of the previously reported diruthenium μ-allenyl complex [Ru2(Cp)2(CO)2(μ-CO){μ-η1:η2 α,β-C(H)=C=C(Me)2}][BF4] (4a) and of the new one [Ru2(Cp)2(CO)2(μ-CO){μ-η1:η2 α,β-C(H)=C=C(Ph)2}][BF4] (4b) have been investigated. The reaction of 4b with Brönsted base results in formation of the μ-allenylidene derivative [Ru2Cp2(CO)2(2-CO){2-η1:η1-C=C=C(Ph)2}] (10). The nitrile adducts [Ru2Cp2(CO)(NCMe)(2-CO){2-η1:η2-C(H)=C=C(R)2}]+ (R = Me, 6a; R = Ph, 6b), prepared by treatment of 4a,b with MeCN/Me3NO, react with N2CHCO2Et/NEt3 at room temperature affording the butenolide-substituted carbene complexes [Ru2Cp2(CO)(2-CO){μ-η 1:η 3-Cα(H)CβCγ(R)2OC(=O)C(H)] (R = Me, 13a; R = Ph, 13b). The intermediate cationic [Ru2Cp2(CO)(2-CO){μ-η 1:η 3-Cα(H)CβCγ(Me)2OC(OEt)C(H)]+ (12) has been detected in the course of the reaction leading to 13a. Alternatively, the addition of N2CHCO2Et/NHEt2 to 4a gives the 2-furaniminium-carbene [Ru2Cp2(CO)(2-CO){μ-η 1:η 3-Cα(H)CβCγ(Me)2OC(NEt2)C(H)]+ (14). The X-Ray structures of [4a][BPh4], [4c][BPh4], 13a, 13b and [14][BF4] have been determined. The novel cationic diiron μ-allenyl complexes [Fe2(Cp)2(CO)2(μ-CO){μ-η1:η2 α,β- C(H)=C=C(R)2}][BF4] (R = Me, 7a; R = Ph, 7b) have been obtained in good yields by a two-step reaction starting from [Fe2Cp2(CO)4]. The solid state structures of [7a][CF3SO3] has been ascertained by X-Ray diffraction studies. The reaction of 7a with Brönsted bases yields the dimetallacyclopentenone [Fe2Cp2(CO)(2-CO){2-η1:η3- C(H)=C(C(Me)CH2)C(=O)}] (16). The reactions of 7a,b with MeCN/Me3NO result in prevalent decomposition to mononuclear iron species. The diiron μ-vinyl complex [Fe2Cp2(CO)(2-CO){2-μ1:μ2-CH=CH(Ph)}][BF4], 9, undergoes reduction by means of CoCp2 affording selectively the C−C coupling Fe4 compound [Fe2Cp2(CO)2(μ-CO){2-μ2-CHCH(Ph)}]2, 16. The cation [9]+ has been regenerated from 16 in good yield upon treatment with I2. Electrochemical studies have outlined that the reduction of 9 to 16, occurring at -0.92V, is reversible and proceeds with intermediate formation of the radical species [Fe2Cp2(CO)2(2-CO){2- CHCH(Ph)}], 17. This latter has been characterized by EPR spectroscopy. The structures of 9, 16 and 17 have been optimized for the gas phase by DFT calculations; the computed enthalpy related to the equilibrium 17 16 is CH = −12.25 KJ·mol−1. The reaction of 9 with CoCp2 in the presence of excess PhSSPh affords the mononuclear complex [Fe2Cp2(CO)2(μ-CO){2-μ2-CHCH(Ph)(SPh)}], 18, in 70% yield. The new compounds 16 and 18 have been fully characterized by IR and NMR spectroscopy, elemental analysis and X-Ray diffraction studies.

The chemistry of unsaturated hydrocarbyl ligands bridging coordinated in diiron or diruthenium complexes / Boni, Adriano; relatore: Pampaloni, Guido; Scuola Normale Superiore, 2011.

The chemistry of unsaturated hydrocarbyl ligands bridging coordinated in diiron or diruthenium complexes

Boni, Adriano
2011

Abstract

The reactivity of the previously reported diruthenium μ-allenyl complex [Ru2(Cp)2(CO)2(μ-CO){μ-η1:η2 α,β-C(H)=C=C(Me)2}][BF4] (4a) and of the new one [Ru2(Cp)2(CO)2(μ-CO){μ-η1:η2 α,β-C(H)=C=C(Ph)2}][BF4] (4b) have been investigated. The reaction of 4b with Brönsted base results in formation of the μ-allenylidene derivative [Ru2Cp2(CO)2(2-CO){2-η1:η1-C=C=C(Ph)2}] (10). The nitrile adducts [Ru2Cp2(CO)(NCMe)(2-CO){2-η1:η2-C(H)=C=C(R)2}]+ (R = Me, 6a; R = Ph, 6b), prepared by treatment of 4a,b with MeCN/Me3NO, react with N2CHCO2Et/NEt3 at room temperature affording the butenolide-substituted carbene complexes [Ru2Cp2(CO)(2-CO){μ-η 1:η 3-Cα(H)CβCγ(R)2OC(=O)C(H)] (R = Me, 13a; R = Ph, 13b). The intermediate cationic [Ru2Cp2(CO)(2-CO){μ-η 1:η 3-Cα(H)CβCγ(Me)2OC(OEt)C(H)]+ (12) has been detected in the course of the reaction leading to 13a. Alternatively, the addition of N2CHCO2Et/NHEt2 to 4a gives the 2-furaniminium-carbene [Ru2Cp2(CO)(2-CO){μ-η 1:η 3-Cα(H)CβCγ(Me)2OC(NEt2)C(H)]+ (14). The X-Ray structures of [4a][BPh4], [4c][BPh4], 13a, 13b and [14][BF4] have been determined. The novel cationic diiron μ-allenyl complexes [Fe2(Cp)2(CO)2(μ-CO){μ-η1:η2 α,β- C(H)=C=C(R)2}][BF4] (R = Me, 7a; R = Ph, 7b) have been obtained in good yields by a two-step reaction starting from [Fe2Cp2(CO)4]. The solid state structures of [7a][CF3SO3] has been ascertained by X-Ray diffraction studies. The reaction of 7a with Brönsted bases yields the dimetallacyclopentenone [Fe2Cp2(CO)(2-CO){2-η1:η3- C(H)=C(C(Me)CH2)C(=O)}] (16). The reactions of 7a,b with MeCN/Me3NO result in prevalent decomposition to mononuclear iron species. The diiron μ-vinyl complex [Fe2Cp2(CO)(2-CO){2-μ1:μ2-CH=CH(Ph)}][BF4], 9, undergoes reduction by means of CoCp2 affording selectively the C−C coupling Fe4 compound [Fe2Cp2(CO)2(μ-CO){2-μ2-CHCH(Ph)}]2, 16. The cation [9]+ has been regenerated from 16 in good yield upon treatment with I2. Electrochemical studies have outlined that the reduction of 9 to 16, occurring at -0.92V, is reversible and proceeds with intermediate formation of the radical species [Fe2Cp2(CO)2(2-CO){2- CHCH(Ph)}], 17. This latter has been characterized by EPR spectroscopy. The structures of 9, 16 and 17 have been optimized for the gas phase by DFT calculations; the computed enthalpy related to the equilibrium 17 16 is CH = −12.25 KJ·mol−1. The reaction of 9 with CoCp2 in the presence of excess PhSSPh affords the mononuclear complex [Fe2Cp2(CO)2(μ-CO){2-μ2-CHCH(Ph)(SPh)}], 18, in 70% yield. The new compounds 16 and 18 have been fully characterized by IR and NMR spectroscopy, elemental analysis and X-Ray diffraction studies.
2011
CHIM/03 CHIMICA GENERALE E INORGANICA
Chimica
Chemistry
Scuola Normale Superiore
Pampaloni, Guido
Barone, Vincenzo
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/85790
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