Selective Photooxidation of Sulfides Catalyzed by Bis-cyclometalated Ir^III Photosensitizers Bearing 2,2'-Dipyridylamine-Based Ligands

A new family of heteroleptic bis-cyclometalated Ir^III complexes with formula [Ir(CN^ )₂ (NN^ )]Cl (CN^ =2-phenylpyridinate and NN^ =2,2'-dipyridylamine or N-benzylated 2,2'-dipyridylamines, were synthesized, characterized, and successfully used as photosensitizers in the catalytic photooxidation of an array of dialkyl, dibenzyl, alkyl aryl, and diaryl sulfides, as well as sulfur-containing amino acids. Furthermore, the reactions proceeded with optimal chemoselectivity, and atom economy under mild conditions. Experimental observations support a dual mechanism in which singlet oxygen and superoxide are the actual oxidants.