Synthesis and Structural Studies of Chiral Indium(III) Complexes Supported by Tridentate Diaminophenol Ligands

Indium(III) dimethyl, dihalide, and alkoxy-bridged complexes bearing a chiral diaminophenoxy tridentate ligand [NNHO]− were synthesized. The dimethyl complex (NNHO)InMe2 (1) was unreactive toward ethanol and 2-propanol and only partially reactive toward the more acidic phenol. The dihalide complexes (NNHO)InX2 (X = Cl (3), Br (4), I (5)) reacted with NaOEt to form robust alkoxy-bridged complexes with the formula {[(NNHO)InX]2(μ-X)(μ-OEt)} (X = Cl (6), Br (7), I (8)). The reaction of the alkoxy-bridged complexes with water produced hydroxy-bridged dinuclear indium compounds. The hydroxy-bridged complex bearing a chloride ligand [(NNHO)InCl(μ-OH)]2 (9) was significantly more reactive toward dissociation and formation of a pyridine adduct than the iodo analogue [(NNHO)InI(μ-OH)]2 (10). All compounds were fully characterized in solution by NMR spectroscopy and in the solid state by single-crystal X-ray diffraction. In addition, DFT calculations were used to help explain the reactivity trends observed.