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

The reactions of the MCl4(PMe3)2 (M = Nb, Hf) complexes with four equivalents of K(6,6-dmch) (dmch = dimethylcyclohexadienyl) lead to complexes with the stoichiometries Nb(6,6-dmch)3(PMe3) and Hf(6,6-dmch)4(PMe3). In each case, only one simple 6,6-dmch ligand remains, while the others have undergone intramolecular couplings, leading to crystallographically characterized complexes with 18 electron configurations.