| Research Abstract |
In order to synthesize novel iridium(V) nitride (or iridium(III) nitrenide) complexes which are expected to show interesting nitrogen-atom transfer reactions, photolysis of iridium(III) azide precursors have been examined. In the case of (pentamethylcyclopentadienyl)(azido)iridium(III) complex having a 2-pyridinethiolate as a co-ligand, [Cp^*Ir(2-Spy)(N_3)], a nitrogen-atom originated from the azide was inserted into the Ir-N(py) bond, affording a five-coordinate complex with a two-legged piano stool structure, [Cp^*Ir(1-N-2-Spy)]. This complex reacted with methyl iodide (as an electrophile) to give an air-stable complex bearing a new didentate imine/thiolate-type ligand, [Cp^*Ir(1-NMe-2-Spy)]I. It was found that both of the ligands, 1-N-2-Spy^<2-> and 1-NMe-2-Spy^-, have a sufficient π-donicity to stabilize a coordinatively unsaturated Ir(III) center in the five-coordinated complexes. These results are indicative of usability of nitrogen-atom transfer process for syntheses of nitrogen
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-containing organic ligands via photolysis of the azide complexes.
Aiming to find another types of photochemical reactivity, several new iridium(III) azide complexes with various co-ligands have been prepared. Among them, we could obtain structurally very interesting complexes. For example, in the case of 1,8-naphthylidine or benzimidazole-2-thiolate, dinuclear complexes with characteristic bridging structures have been revealed by X-ray analyses. Furthermore, when the azido complexes with co- ligand of 2,2'-bipyridine or 1,10-phenanthroline were photolyzed, unexpected dinuclear complexes bridged asymmetrically by 5-methyltetrazolate were resulted via 1,3-dipolar cycloaddition of the solvent acetonitrile to the coordinated azide ligand.
In summary, this study developed new synthetic methods for nitrogen-containing organic compounds by photolysis of iridium(III) azide complexes, in which novel iridium(V) nitride or iridium(III) nitrenide intermediates would be formed, and the nitrogen-atom transfer process from the complexes would be a key step in these reactions. Less
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