PdII, ZnII and AgI Complexes of Tetrakis(N‐7‐azaindolyl)benzene: Variation of Bonding Modes, Extended Structures and Luminescence

PdII, AgI and ZnII complexes of tetrakis(7‐azaindolyl)benzene (ttab), [(PdCl2)2(ttab)] (1), [(ZnCl2)2(ttab)] (2), [Ag(NO3)]2(ttab) (3a) and [Ag(NO3)(DMSO)]2(ttab) (3b) were synthesized and fully characterized by NMR spectroscopy, single‐crystal X‐ray diffraction and elemental analyses. The ttab ligand in these complexes displays two different bonding modes. In the PdII and ZnII complexes, the ttab ligand chelates to the metal center via two ortho 7‐azaindolyl groups (the ortho mode). In contrast, in the AgI complex, it chelates to the AgI ion via two meta 7‐azaindolyl groups (the meta mode). In the solid state, molecules of 1 and 2 form grid‐like extended structures that host solvent molecules such as DMSO and CH2Cl2. Compound 3a appears to be a coordination polymer and can be converted into compound 3b when dissolved in DMSO. A hydrogen bonded complex [Zn(O2CCF3)2(H2O)2](ttab) (4), which displays an unusual hydrogen bonded helical chain structure in the solid state, was also characterized. Except for compound 1, these new compounds all emit blue light when irradiated by UV radiation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)