Synthesis and characterization of cyclohexadienyl-based constrained geometry complexes

The novel constrained geometry complexes [eta(5):eta(1)-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 dimethylsilacyclo hexadienyl ligands have been prepared and characterized by H-1 and C-13{H-1 } NMR spectroscopy and single-crystal X-ray structure analysis (5a and 6a). These complexes are the first examples of compounds containing eta(5) "ope n" dienyl ligands (pentadienyl or cyclohexadienyl) for titanium in its high est (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.