Synthesis, reactivity, and catalytic application of tetraphenylcyclobutadiene iridium complexes

Reaction of [(coe)₂IrCl]₂ (coe = cyclooctene) with AgPF₆, arene (toluene, p-xylene, mesitylene), and diphenylacetylene, followed by counter anion exchange to BARF^–, gives cyclobutadiene iridium complexes [(C₄Ph₄)Ir(arene)]BARF in 10–22% yield. Replacement of toluene in [(C₄Ph₄)Ir(toluene)]BARF by various ligands (trimethyl-phosphite, 1,3,5-triaza-7-phosphaadamantane, tert-butyl isonitrile) provides access to the half-sandwich cyclobuta-diene iridium complexes [(C₄Ph₄)Ir(L)₃]BARF. Complex [(C₄Ph₄)Ir(toluene)]BARF in combination with [NBnEt₃]Cl catalyses the insertion reaction between phenyl diazoacetate and various amines.