Coordination chemistry of half-open trozircenes: Adduct formation of [(η7-C7H7)Zr(η5-2,4-C7H11)] with isocyanides, phosphines and N-heterocyclic carbenes

The reactions of the half-open trozircene [(η7-C7H7)Zr(η5-2,4-C7H11)] (1) with the two-electron donor ligands tert-butyl isocyanide (CN-tBu), 1,2-bis(dimethylphosphino)ethane (dmpe), trimethylphosphine (PMe3) and 1,3,4,5-tetramethylimidazolin-2-ylidene (IMe, :C[N(Me)C(Me)]2) have led to the 1:1 adducts 3, 4, 5 and 6, respectively. The latter three were structurally characterized by X-ray diffraction analysis. Additionally, the stability of the adducts was probed by DFT calculations employing the B3LYP and M05-2X functionals showing that the strongly σ-basic N-heterocyclic carbene forms a thermodynamically much more stable adduct than the other three.