Reactions of Titanocene- and Zirconocene-Bis(trimethylsilyl)acetylene Complexes with Selected Heterocyclic and Aromatic NH and OH Acid Compounds

Abstract

The titanocene complexes Cp'2Ti(η2-Me3SiC2SiMe3) (Cp' = Cp (1), Cp* (2)) react with pyrrole under the formation of the titanium(III) mono-N-pyrrolides Cp'2Ti(NC4H4) (Cp' = Cp (6), Cp* (7)); whereas the corresponding zirconocene system Cp2Zr(η2-Me3SiC2SiMe3)(thf) (3) forms in a different reaction pathway first the Cp2Zr(NC4H4)[C(SiMe3)=CH(SiMe3)] (8) and then the zirconium(IV) bis-N-pyrrolide Cp2Zr(NC4H4)2 (11). With Cp*2Zr(η2-Me3SiC2SiMe3) (4) and pyrrole, the zirconium(IV) mono-N-pyrrolide with an agostic alkenyl group Cp*2Zr(NC4H4)[C(SiMe3)=CH(SiMe3)] (9) was obtained. In the reaction of the ethylenebistetrahydroindenyl (ebthi) complex rac-(ebthi)Zr(η2-Me3SiC2SiMe3) (5) with 2,3,5,6-tetrafluoroaniline under N-H bond activation, a complex with an agostic alkenyl group rac-(ebthi)Zr(NH-C6HF4)[C(SiMe3)=CH(SiMe3)] (10) was formed. Compound 10 reacts with additional 2,3,5,6-tetrafluoroaniline to give the bisanilide rac-(ebthi)Zr(NH-C6HF4)2 (12) which was obtained directly from 5 with two equivalents of 2,3,5,6-tetrafluoroaniline. In reactions of complex 5 with unsubstituted aniline to rac-(ebthi)Zr(NH-C6H5)2 (13) and with pentafluorophenol to bisphenolate rac-(ebthi)Zr(O-C6F5)2 (14), no intermediates could be isolated. The new reaction products 6, 9, 10, 12, 13 and 14 were investigated by X-ray crystallography.