Elaborate Network of Hydrolysis and Methanolysis Reactions involving the 2,5-Dimethylthiophene Ligand in Cp*Ir(η 5-2,5-Me 2T) 2+

M. Angeles Paz-Sandoval, Marisol Cervantes-Vasquez, Victor G. Young, Ilia A. Guzei, Robert J. Angelici

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Abstract

Reactions of aqueous base with the dicationic iridium and rhodium thiophene complexes [Cp*Ir(η 5-2,5-Me 2T)](X) 2 (X = BF 4,1(BF 4); X = OSO 2CF 3, 1(OTf)) and [Cp*Rh(η; 5-2,5-Me 2T)]-(BF 4) 2 (8(BF 4)) and the acid/base reactivity of these products are discussed. The reaction of 1(BF 4) with 1 equiv of aqueous KOH (0.01 M) affords the following mixture of mono-, di-, and tetranuclear compounds: [Cp*Ir(eta; 4-SC(Me)CHCHC(O)Me)] (3), (Cp*Ir)[Cp*Ir(η 4-SC-(Me)CHCHC(O)Me)] 3(BF 4) 2 (4(BF 4)), [(Cp*Ir) 224-SC(Me)CHCC(O)Me)](BF 4) (5(BF 4)), and [Cp*Ir(μ2,η 3-SC(Me)CHCH 2C(O)Me)] 2(BF 4) 2 (6(BF 4)). The 1H and 13C NMR data are consistent with the single-crystal X-ray diffraction structures of the cationic complexes 4-(BF 4), 5(OTf), and 6(BF 4). These products are formed by a complex series of reactions that begin with the displacement of the 2,5-dimethylthiophene (2,5-Me 2T) ligand from 1 and reaction of the resulting "[Cp*Ir] 2+" fragment with 3. In the synthesis of 8(BF 4), the new complex [(Cp*Rh) 224-SC(Me)CHCC(O)Me)](BF 4) (9(BF 4)), analogous to 5(BF 4), is produced. Studies of the reactions of [Cp*Rh(η 5-2,5-Me 2T)](BF 4) 2 (8(BF 4)) with OH - and MeO - show a type of reactivity quite different from that observed for 1(BF 4) and 1(OTf). The solvolysis of 8(BF 4) in acetone affords the mononuclear complex [Cp*Rh(OCMe 2) 2(OH)](BF 4) (10(BF 4)), whose crystal structure is described. Detailed NMR studies establish the pathways by which [Cp*Ir(η 5-2,5-Me 2T)] 2+ (1) and [Cp*Rh(η 5-2,5-Me 2T)] 2+ (8) react with H 2O/OH - and MeOH/MeO - to give the variety of observed products.

Original languageEnglish (US)
Pages (from-to)1274-1283
Number of pages10
JournalOrganometallics
Volume23
Issue number6
DOIs
StatePublished - Mar 15 2004

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