Addition of the dilithium salt, ortho-(Me₃SiNLi)₂C₆H₄, to ZrCl₄ affords a base-free, D_2d-symmetric complex Zr^IV[ortho-(Me₃SiN)₂C₆H₄]₂ (2), with rigorously planar ortho-phenylenediamine ligands. Lewis acidic 2 readily coordinates donor ligands such as NHEt₂ to give the five-coordinate complex, Zr^IV(NHEt₂)[ortho-(Me₃SiN)₂C₆H₄]₂ (3), which is also accessible by the reaction of Zr(NEt₂)₄ with 2 equiv of ortho-(Me₃SiNH)₂C₆H₄. Aryl azides react with 2 and 3 to give an unusual tetra-azametallacycle complex, 4, via 1,2-addition of a ligand N−Si bond to the organic azide. An X-ray crystal structure of 4 reveals a planar, five-membered metallacycle comprising the zirconium atom, one nitrogen atom of the ortho-(Me₃SiN)₂C₆H₄ ligand, and all three nitrogen atoms of the aryl azide.