New mononuclear osmium complexes M1-M4 with various NCN-cyclometalating pyrene ligands were synthesized and thoroughly characterized with particular emphasis on the nature of NCN-cyclometalating pyrene ligands on the properties of target compounds. Structural properties were achieved by using the theoretical studies (DFT). Moreover, spectroscopic and theoretical studies (TD-DFT) show the character of transi-[a] 5117 Scheme 1. Synthesis of NCN-cyclometalating pyrene ligand containing 2-butyl-2H-1,2,3,4-tetrazol-5-yl substituents. Reagents and conditions: a) CuCN, NMP, 180°C, 48 h; b) NaN 3 NH 4 Cl, DMF, 120°C, 10 h; c) butyl bromide, K 2 CO 3 , DMF, 70°C, 24 h. Scheme 3. Synthesis of the designed complexes M1-M4. Reagents and conditions: a) Os-TPY, NCN-pyrene ligand, ethylene glycol, 199°C, 24 h.

π‐Extended acenaphtho[1,2‐d][1,2,3]triazoles, the unsubstituted Anta‐H and its di‐tert‐butyl derivative Dibanta‐H, as well as 5,6,7,8‐tetrahydro‐1H‐naphtho[2,3‐d][1,2,3]triazole Cybta‐H were obtained in concise syntheses. In the solid state, Dibanta‐H forms an unprecedented hydrogen‐bonded cyclic tetrad, stabilized by dispersion interactions of the bulky tBu substituents, whereas a cyclic triad was found in the crystal structure of Anta‐H. These cyclic assemblies form infinite slipped stacks in the crystals. Evidence for analogous hydrogen‐bonded self‐assembly in solution was provided by low‐temperature NMR spectroscopy and computational analyses. Kuratowski‐type pentanuclear complexes [Zn5Cl4(Dibanta)6] and [Zn5Cl4(Cybta)6] were prepared from the respective triazoles. In the Dibanta complexes, the π‐aromatic surfaces of the ligands extend from the edges of the tetrahedral Zn5 core, yielding an enlarged structure with significant internal molecular free volume and red‐shifted fluorescence.