%0 Journal Article 
%A Royo Gracia, Pascual
%A Sánchez-Nieves Fernández, Javier
%T Oxo and imido/imido exchange and C-H activation reactions based on pentamethylcylopentadienyl imido tantalum complexes
%D 2000
%@ 0022-328X
%U http://hdl.handle.net/10017/4209
%X Reactions of [TaCp*Cl4] with two, three and four equivalents of LiNHt
Bu give the halo- and amido-imido complexes
[TaCp*Cl2(Nt
Bu)] (1a), [TaCp*Cl(Nt
Bu)(NHt
Bu)] (2) and [TaCp*(Nt
Bu)(NHt
Bu)2] (3), respectively. The related complex
[TaCp*Cl2{N(2,6-Me2C6H3)}] (1b) is prepared by a similar reaction using two equivalents of Li[NH(2,6-Me2C6H3)]. Complex 3
can be transformed into 2 and further into 1a by reaction with SiClMe3. Complex 1a reacts with CNt
Bu to give the 18-electron
adduct [TaCp*Cl2(Nt
Bu)(CNt
Bu)] (4) whereas addition of excess CN(2,6-Me2C6H3) results in reductive elimination of the
carbodiimide t
BuN C N(2,6-Me2C6H3) (5) to give [TaCp*Cl2{CN(2,6-Me2C6H3)}3]. However complex 1b does not react with any
of the isocyanide ligands. Both complexes 1a and 1b react with PhCHO undergoing imido/oxo exchange to give the imines
PhCH NR (R=t
Bu, 2,6-Me2C6H3 (6)) and dimeric [TaCp*Cl2(O)]2 or trimeric [(TaCp*Cl)3(m2-Cl)(m2-O)3(m3-O)] oxo-complexes,
whereas only 1a reacts with CO2, PhCH NR% (R%=Ph, Me) and (2,6-Me2C6H3)N C Nt
Bu producing t
BuN CO, PhCH Nt
Bu
and t
BuN C Nt
Bu, respectively and the corresponding oxo or imido tantalum derivative. None of the complexes reacts with
CO or NCR (R=Me, Ph). The complex [TaCp*Me(Nt
Bu)(NHt
Bu)] activates C–H bonds when heated in benzene and toluene
affording [TaCp*Ph(Nt
Bu)(NHt
Bu)] (7) and a mixture of [TaCp*(m-MeC6H4)(Nt
Bu)(NHt
Bu)] 8a and [TaCp*(pMeC6H4)(Nt
Bu)(NHt
Bu)] (8b). All of the reported organic compounds and tantalum complexes were characterized by 1
H- and 13C-NMR spectroscopy
%K Oxo/imido imido/imido exchange
%K C-H activation
%K Cyclopentadienyl imido tantalum complexes
%K Ciencia
%K Química inorgánica
%K Science
%K Chemistry, inorganic
%~ Biblioteca Universidad de Alcala