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)(2)M (cod)], prepared by reactions of the lithium salt of the ligand with [M(mu-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)(3)SiMe2(CH2)(3)B(CH2PPh2)(pz)(2)}(4)], which leads further to the corresponding metallodendrimer with four rhodium atoms.