Luminescent\nBis(amidinate) Indium Complexes

Bis-amidinate indium(III) monochlorides [(<i><sup>t</sup></i>BuN)<sub>2</sub>C(Ph)]<sub>2</sub>InCl (<b>1</b>), [(<i><sup>t</sup></i>BuN)<sub>2</sub>C(2-naphthyl)]<sub>2</sub>InCl\n(<b>2</b>), [(<i><sup>t</sup></i>BuN)<sub>2</sub>C(2-anthryl)]<sub>2</sub>InCl (<b>3</b>), [(<i><sup>t</sup></i>BuN)<sub>2</sub>C(9-anthryl)]<sub>2</sub>InCl (<b>4</b>), [(<i><sup>t</sup></i>BuN)<sub>2</sub>C(9-phenanthryl)]<sub>2</sub>InCl (<b>5</b>), and [(<i><sup>t</sup></i>BuN)<sub>2</sub>C(1-pyrene)]<sub>2</sub>InCl (<b>6</b>) were prepared\nby the reaction of the corresponding Li-amidinate ligand with InCl<sub>3</sub>. Single crystal X-ray analysis of compounds <b>1</b>, <b>2</b>, <b>4</b>, and <b>5</b> reveals that\nthe In(III) center is bound with two chelating amidinate ligands.\nThe overall coordination geometry around In(III) is distorted trigonal\nbipyramidal with the chloride occupying one of the equatorial positions.\nThe photophysical properties of these compounds have been analyzed.\nCompounds <b>2</b>–<b>6</b> are emissive in the\nsolution state. The 9-anthryl substituted compound <b>4</b> was\nfound to exhibit a maximum quantum yield of 45.5% in dichloromethane.\nCompound <b>3</b> has a maximum lifetime of 11 ns in solution.\nTheoretical studies were performed to validate the photophysical properties\nobserved in these compounds.