Unprecedented Hybrid Scorpionate/Phosphine Ligand Able To Be Anchored to Carbosilane Dendrimers

The synthesis of a novel hybrid pyrazolate/phosphine anionic ligand
[CH2CHCH2B(CH2PPh2)(pz)2]- is described. Coordination of this
ligand to metals in a fac tridentate fashion occurs in the complexes
[CH2CHCH2B(CH2PPh2)(pz)2M(cod)], prepared by reactions of
the lithium salt of the ligand with [M(μ-Cl)(cod)]2 (M = Rh, Ir).
They are pentacoordinated, with the rhodium complex showing a
distorted trigonal-bipyramidal structure in the solid state, as
determined by X-ray diffraction methods. Furthermore, the ligand
has been linked to the periphery of a carbosilane dendrimer,
resulting in the polyanionic dendrimer [Li(TMED)]4[Si{(CH2)3SiMe2(CH2)3B(CH2PPh2)(pz)2}4], which leads further to the corresponding
metallodendrimer with four rhodium atoms.