Addition of the dilithium salt, ortho-(Me3SiNLi)(2)C6H4, to ZrCl4 affords a base-free, D(2sigma)symmetric complex Zr-IV[ortho-(Me3SiN)(2)C6H4](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)(2)C6H4](2) (3), which is also accessible by the reaction of Zr(NEt2)(4) with 2 equiv of ortho-(Me3SiNH)(2)C6H4. 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)(2)C6H4 ligand, and all three nitrogen atoms of the aryl azide.