The utility of polydentate monoanionic [Zr-2((OPr)-Pr-i)(9)](-) in generating arene-soluble, unsolvated, mixed-metal Zr/Ce and Zr/Y complexes is described. The synthesis of other mixed-metal zirconium lanthanide complexes was also studied to explore the relationship of metal size to structure. Lanthanide trihalides react in THF with KZr2((OPr)-Pr-i)(9) to form unsolvated dimers, {[Zr-2((OPr)-Pr-i)(9)](-)LnCl(2)}(2), with the larger metals, Ln = Ce (1), Ho (2), Y (3), and unsolvated monomers, [Zr-2((OPr)-Pr-i)(9)]LnCl(2), with the smaller elements, Ln = Er (4), Yb (5). The synthesis of a monomeric iodide analogue, [Zr-2((OPr)-Pr-i)(9)]TmI2, 6, by reduction of Zr-2((OPr)-Pr-i)(8)((PrOH)-Pr-i)(2) with TmI2(DME)(3) is also reported. In all of these complexes, the [Zr-2((OPr)-Pr-i)(9)](-) subunit is tetradentate. 1-6 are compared with related cyclopentadienyl halide complexes to evaluate the special features of the dizirconium nonaisopropoxide ligand versus cyclopentadienide.