Metallacycles or coexistence of isomeric metallacycle and chain: Anion-dependent luminescent Ag complexes of a flexible diaminotriazine–imidazole ligand

• Five Ag complexes were obtained using a flexible diaminotriazine–imidazole ligand.
• Cocrystal structures of ring-opening isomers were observed in 1 and 2.
• Both the diaminotriazine and the imidazole group participate in coordination.
• TGA and emission behaviors of the complexes were investigated.

Reaction of a flexible ligand 2,4-diamino-6-[2-(2-methyl-1-imidazolyl) ethyl]-1,3,5-triazine (L) with Ag(I) in the presence of different counteranions afforded five complexes, namely, 2[Agn(L)n(NH3)n]··n[Ag2(L)2(NH3)2]··2n(nds) (1, H2nds = 1,5-naphthalenedisulfonic acid), 2[Agn(L)n]··n[Ag2(L)2(CF3CO2)2]··nCF3CO2 (2), [Ag2(L)2(NH3)2]··2(ClO4) (3), [Ag2(L)2]··2(NO3) (4), [Ag2(L)2]··2(ClO3) (5), which were characterized by element analysis, IR, PXRD and X-ray single-crystal diffraction. Structural analysis reveals that the L ligand take the same bidentate coordination mode in these complexes. The nds anion and the CF3CO2- anion lead to the coexistence of isomeric metallacycle and helical chain (ring-opening isomers) in the crystals of 1 and 2, while ClO4-,NO3- and ClO3- anions afford dimeric metallacycles in complexes 3–5. Moreover, thermal gravity analysis (TGA) and emissive behaviors of these complexes were investigated.

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