199939-53-2Relevant academic research and scientific papers
A cationic imido complex of permethyltantalocene: H2 and carbon-hydrogen bond activation, [2 + 2] cycloaddition reactions, and an unusual reaction with carbon dioxide That affords coordinated isocyanate
Blake Jr., Robert E.,Antonelli, David M.,Henling, Larry M.,Schaefer, William P.,Hardcastle, Kenneth I.,Bercaw, John E.
, p. 718 - 725 (2008/10/08)
Treatment of the imido hydride complex Cp*2Ta(=NCMe3)H (Cp* = (η5-C5Me5)) with [Ph3C]-[B(C6F5)4] in tetrahydrofuran solution yields the cationic imido complex [Cp*2Ta(=NCMe3)-(THF)][B(C6F 5)4] (1). Cation 1 reacts cleanly with H2 to yield [Cp*2Ta(NHCMe3)H][B(C6F5)4]. Carbon-hydrogen bond-activation reactions are observed with propyne or phenylacetylene to afford [Cp*2Ta(NHCMe3)(C=CR)][B(C6F 5)4] (R = CH3, C6H5). In the reaction with propyne, an initial mixture of the [2 + 2] cycloaddition product and C-H activation product is thermally driven to the C-H activation product. The heterolytic cleavage reactions for 1 may be rationalized in terms of the presence of both electrophilic and nucleophilic sites of reactivity in the same molecule. Intramolecular activation of a carbon-hydrogen bond of a Cp* methyl group to ultimately yield [Cp*Ta(η5-C5Me4CH 2NCMe3)H][B(C6F5)4] precludes C-H activation of the carbon-hydrogen bonds of methane. An unusual reaction occurs with carbon dioxide: dealkylation of the imido group is observed, liberating isobutylene and yielding the isocyanate complex [Cp*2Ta(OH)(NCO)][B(C6F5)4]. Complex 1 reacts with HCl to afford [Cp*2Ta(NHCMe3)Cl][B(C6F 5)4] and decomposes cleanly in methylene chloride solution to give [Cp*2Ta(NHCMe3)Cl][B(C6F 5)4] by formal HCl abstraction. X-ray crystal structure determinations for [Cp*Ta(η5-C5Me4CH 2NCMe3)H][B(C6F5)4], [Cp*2Ta-(NHCMe3)Cl][B(C6F 5)4], [Cp*2Ta(NHCMe3)H][B(C6F5) 4], [Cp*2Ta(NHCMe3XC=CC6H 5)][B(C6F5)4] and [Cp*2Ta(OH)(NCO)][B(C6F5)4] are reported.
