Synthesis and Characterization of Cyclohexadienyl-Based Constrained Geometry Complexes

The novel constrained geometry complexes [η5:η1-C5H4EMe2−SiMe2−N(t-Bu)]TiX2, 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 1H and 13C{1H} NMR spectroscopy and single-crystal X-ray structure analysis (5a and 6a). These complexes are the first examples of compounds containing η5 “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.