1. ansa-Cyclopentadienyl-Arene Tantalum Complexes: Structure and Reactivity of Neutral, Cationic, and Dicationic Derivatives.
- Author
-
Otten, Edwin, Meetsma, Auke, and Hessen, Bart
- Subjects
- *
AROMATIC compounds , *TANTALUM compounds , *METAL complexes , *REACTIVITY (Chemistry) , *MOLECULAR structure , *CATIONS , *CHEMICAL derivatives , *ALKENES - Abstract
The cationic tantalum complex {[η6-Ar-CMe2-η5-C5H4]TaPr}[B(C6F5)4] (1; Ar = 3,5-Me2C6H3) serves as a starting materialfor a series of neutral, monocationic, and dicationic derivatives.The cationic hydride {[η6-Ar-CMe2-η5-C5H4]TaH}[B(C6F5)4] (2) that results from hydrogenolysisof 1inserts the di- and trisubstituted olefins cyclopenteneand 2-methyl-2-pentene; it reacts with styrene to give the 2,1-insertionproduct, for which the TaâCH(Me)Ph group is bound in a Ï3-allylic fashion. A neutral complex is obtained from 1by reaction with Brâ, and a dicationicderivative is available by hydride abstraction from 2using the Lewis acidic trityl cation. All compounds described hereretain the unusual ansa-(η5-cyclopentadienyl,η6-arene) coordination mode of the ligand that stabilizes theformally Ta(III) center. X-ray structures and DFT calculations showthat the metalâarene interaction contains a significant Ïback-donation component (areneâTa(III)) that differs only slightlyin the series, despite the variation of charge at the metal center. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF