Construction of tetranuclear macrocycles through C-H activation and structural transformation induced by [2+2] photocycloaddition reaction.
A series of binuclear complexes [{Cp*Ir(OOCCH(2)COO)}(2)(pyrazine)] (1b), [{Cp*Ir(OOCCH(2)COO)}(2)(bpy)] (2b; bpy=4,4'-bipyridine), [{Cp*Ir(OOCCH(2)COO)}(2)(bpe)] (3b; bpe=trans-1,2-bis(4-pyridyl)ethylene) and tetranuclear metallamacrocycles [{(Cp*Ir)(2)(OOC-C=C-COO)(pyrazine)}(2)] (1c), [{(Cp*Ir)(2)(OOC-C=C-COO)(bpy)}(2)] (2c), [{(Cp*Ir)(2)(OOC-C=C-COO)(bpe)}(2)] (3c), and [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](pyrazine)}(2)] (1d), [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](bpy)}(2)] (2d), [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](bpe)}(2)] (3d) were formed by reactions of 1a-3a {[(Cp*Ir)(2)(pyrazine)Cl(2)] (1a), [(Cp*Ir)(2)(bpy)Cl(2)] (2a), and [(Cp*Ir)(2)(bpe)Cl(2)] (3a)} with malonic acid, fumaric acid, or H(2)ADB (azobenzene-4,4'-chcarboxylic acid), respectively, under mild conditions. The metallamacrocycles were directly self-assembled by activation of C-H bonds from dicarboxylic acids. Interestingly, after exposure to UV/Vis light, 3c was converted to [2+2] cycloaddition complex 4. The molecular structures of 2b, 1c, 1d, and 4 were characterized by single-crystal x-ray crystallography. Nanosized tubular channels, which may play important roles for their stability, were also observed in 1c, 1d, and 4. All complexes were well characterized by (1)H NMR and IR spectroscopy, as well as elemental analysis.
Shanghai Key Laboratory of Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, Shanghai 200433, P. R. China.
Wei-Bin
WB
Yu
Ying-Feng
YF
Han
Yue-Jian
YJ
Lin
Guo-Xin
GX
Jin