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Insertion of Isocyanides into Group 4 Metal−Carbon and Metal−Nitrogen Bonds. Syntheses and DFT Calculations

2003; American Chemical Society; Volume: 22; Issue: 21 Linguagem: Inglês

10.1021/om030211n

1520-6041

Ana M. Martins, José R. Ascenso, C.G. De Azevedo, Alberto R. Dias, M. Teresa Duarte, João Ferreira da Silva, Luı́s F. Veiros, Sandra Rodrigues,

Synthesis and characterization of novel inorganic/organometallic compounds

The reactions of [Ti(η5-Ind)(NMe2)2Me], [Ti(η5-Ind)(NMe2)Cl2], and [Zr(η5-Ind)(NMe2)2Cl] with 2,6-dimethylphenyl isocyanide (CN(2,6-Me2Ph)) and tert-butyl isocyanide (CN-t-Bu) have been investigated. For the first complex, insertion occurs exclusively into the Ti−C bond to give [Ti(η5-Ind)(NMe2)2{C(Me)N-t-Bu}] (1), which, according to DFT results, is due to the weakness of the Ti−CH3 bond when compared to Ti−NR2. [Ti(η5-Ind)(NMe2)Cl2] was found to react with 1 equiv of CN(2,6-Me2Ph) to yield [Ti(η5-Ind){C(NMe2)N(2,6-Me2Ph)}Cl2] (2). Two equivalents of 2,6-dimethylphenyl isocyanide reacts with [Zr(η5-Ind)(NMe2)2Cl] to give the double insertion compound [Zr(η5-Ind){C(NMe2)N(2,6-Me2Ph)}2Cl] (3). The same reaction performed with CN-t-Bu proceeds slowly and enabled the characterization, by NMR, of [Zr(η5-Ind)(NMe2){C(NMe2)N-t-Bu}Cl] (4) and [Zr(η5-Ind){C(NMe2)N-t-Bu}2Cl] (5). The molecular structures of 2 and 3 have been determined by X-ray diffraction. DFT calculations of the insertion of CNH in the zirconium nitrogen bonds of [Zr(η5-Ind)(NR2)2Cl] (R = H, Me) have been performed and show that the progressive stability of the insertion products accounts for the experimentally found double insertion product.