Propene complexes of molybdenum and tungsten stabilized by intramolecular coordination of the 1-(quinol-8-yl)indenyl ligand

Abstract

We report herein a new class of mixed propene-indenyl complexes of molybdenum and tungsten stabilized by a strong N -> M intramolecular coordination. The complexes [{eta(5):kappa N-1-(C9H6N)C9H6}(eta(2)-C3H6)M(CO)(2)][BF4] (M = Mo, W) were obtained in nearly quantitative yields by the protonation of the eta(3)-allyl ligand in compounds [(eta(3)-C3H5){eta(5)-1-(C9H6N)C9H6}M(CO)(2)] (M = Mo, W). In contrast to known eta(2)-alkene molybdenum and tungsten compounds, the species presented here are easily isolated in the solid state. The tungsten compound [{eta(5):kappa N-1-(C9H6N)C9H6}(eta(2)-C3H6)W(CO)(2)][BF4] is stable at room temperature, and its structure was unambiguously confirmed by X-ray diffraction. The reactivity of both propene complexes toward several monodentate donors was examined. In the case of dimethyl sulfide, ligand exchange takes place to afford [{eta(5):kappa N-1-(C9H6N)C9H6}M(CO)(2)(SMe2)][BF4] (M = Mo, W) while acetonitrile induces eta(5) -> eta(3) haptotropic rearrangement to give [{eta(3):kappa N-1-(C9H6N)C9H6}M(CO)(2)(NCMe)(2)][BF4] (M = Mo, W).