Homometallic Rare-Earth Metal Phosphinidene Clusters: Synthesis and Reactivity

Two new trinuclear (3)-bridged rare-earth metal phosphinidene complexes, [{L(Ln)(-Me)}(3)((3)-Me)((3)-PPh)] (L=[PhC(NC(6)H(4)iPr(2)-2,6)(2)](-), Ln=Y (2a), Lu (2b)), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120 degrees C leads to an unprecedented orthoCH bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha-Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS2 leads to the formation of novel trinuclear rare-earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation.