Reactions of the 6,6-dimethylcyclohexadienyl anion with MCl4(PMe3)2 complexes (M = Hf, Nb) : Isolation of complex intramolecular coupling products

Abstract Reactions of NbCl 4 (PMe 3 ) 2 and HfCl 4 (PMe 3 ) 2 with four equivalents of the 6,6-dimethylcyclohexadienyl anion lead to Nb(6,6-dmch)[η 2,4 -(dmch) 2 ](PMe 3 ) and Hf(6,6-dmch)[η 3,4 -(dmch) 3 ](PMe 3 ). Each complex has been crystallographically characterized, and found to contain one η 5 -bound 6,6-dmch ligand, with the other dmch units coupled together to yield olefin, allyl, and diene coordinations, resulting in 18 electron configurations for these compounds.