Synthesis and Characterization of Cyclohexadienyl-Based Constrained Geometry Complexes

The novel constrained geometry complexes [η 5:η 1 -C 5 H 4 EMe 2 −SiMe 2 −N( t -Bu)]TiX 2, 5a (E = C, X = Cl), 5b (E = C, X = Me), 6a (E = Si, X = Cl), and 6b (E = Si, X = Me), based on dimethylcyclohexadienyl and dimethylsilacyclohexadienyl ligands have been prepared and characterized by 1 H and 13 C{ 1 H} NMR spectroscopy and single-crystal X-ray structure analysis ( 5a and 6a ). These complexes are the first examples of compounds containing η 5 “open” dienyl ligands (pentadienyl or cyclohexadienyl) for titanium in its highest (4+) oxidation state. The crystallographic and electrochemical analysis of these complexes demonstrate that “open” dienyl ligands can be used as a viable replacement for the cyclopentadienyl ring in complexes containing a pendant amido group.