Department of Chemistry, Graduate School of Engineering Science, Osaka University
○Tsuneaki Yamagata Takayuki Miyabayashi Takeshi Hara Kazushi Mashima

A tridentate ligand of 6-diphenylphosphanyl-2-pyridonate (pyphos) ligand has three coordination sites, O, N, and P, supported linearly by the rigid pyridone ring. The pyphos ligand acts as coordination sites for arrangements more than two kinds of transition metals in a linear manner. The 6-diphenylphosphanyl-1H-pyridin-2-one/6-diphenylphosphanyl-2-hydroxypyridine tautomer system is known to dimerize in aprotic solvents to form predominantly the symmetrical pyridone dimer through hydrogen bonding, and the Ruthenium and Rhodium complexes having 2-pyridone/2-hydroxypyridine or analogous ligands serve as effective catalyses. We synthesized and crystallized the title complex, containing hydrido, chloro, 6-diphenylphosphanyl-2-hydroxypyridine (pyphosH), and 6-diphenylphosphanyl-2-pyridonate (pyphos) ligands. The structure of the iridium(III) metal centre adopts a distorted octahedron. The N-H bond of the pyphosH ligand is oxidatively added to an iridium atom. The two P and N atoms of the pyphosH and pyphos ligands lie the cis coordination in the basal plane. An intramolecular O-H---O hydrogen bond between pyphosH and pyphos ligands is observed. Spectroscopic date show the presences of the hydrogen bond and the magnetically equivalent phosphorous atoms. Therefore the proton exchange in the O-H---O hydrogen bond would occur in the solution.