Rational Design of Half-Sandwich Iridium Metallamacrocycles Assembled by C-H Activation

Both tetranuclear metallamacrocycles {(Cp*Ir)(2)-[m-(OOC-C6H2-COO)](Pyrazine)}(2) (2a) and {(CP*Ir)(2){m-[OOC-(5-NH2-C6H)-COO)]}(Pyrazine)}(2). (3a) were formed by reactions of {[(Cp*Ir)(2)(pyrazine)Cl-2] (1a) with 1,3-benzenedicarboxylic acid (m-H2BDC) and 5-amino-1,3-benzenedicarboxylic acid (NH2-m-BDC) in the presence of TEA (triethylamine) under mild conditions, respectively. In order to investigate the effect of N-donor ligands in the construction of metallamacrocycles, the binuclear complexes [(Cp*Ir)(2)(bpy)-Cl-2] and [(Cp*Ir)(2)(bpe)Cl-2] were used as precursors to react with m-H2BDC and NH2-m-BDC under the same conditions to result in tetranuclear metallamacrocycles {(Cp*Ir)(2)[m-(CCC-C6H2-COO)](bpy)}(2) (2b), {(CP*Ir)(2)[m-(OOC-C6H2-COO)] (bpe)}(2) (2c), {(CP*Ir)(2){m-[OOC-(5-NH2-C6H)-COO)]}-(bpy)}(2) (3b), and {(Cp*Ir)(2){m-[OOC-(5-NH2-C6H)-COO)]}(bPe)}(2) (3c). Furthermore, in the development of building similar metallamacrocycles by dicarboxylic acid through C-H activation, 2-amino- 1,4-benzenedicarboxylic acid (NH2-BDC) was employed to react with N-donor bridging binuclear complexes, resulting in complexes {(Cp*Ir)(2)[OOC-(2-NH2-C6H)-COO)]-(pyrazine)}(2) (4a), {(CP*Ir)(2)[OOC-(2-NH2-C6H)-COO)(bPY)}(2) (4b), and {(Cp*Ir)(2)[OOC-(2-NH2-C6H)-COO)] (bPe)}(2) (4c). The molecular structures of 2a and 3a were confirmed by single-crystal X-ray crystallography. All complexes were well characterized by NMR, IR, and elemental analysis.