Synthesis, spectral and molecular studies of half-sandwich arene ruthenium and Cp*Rh/Cp*Ir complexes containing bidentate P-N and E–N ligands (E = S, Se) based on diphenyl(2-pyridyl)phosphine

<div><p>The chalcogenide ligands {E=PPh₂Py} (E = O, S, Se) were prepared by direct oxidation of diphenyl(2-pyridyl)phosphine using H₂O₂, S, and Se powder, respectively. The reaction of ligand with starting metal precursors [(arene)RuCl₂]₂ {M = Ru, arene = benzene; <i>p</i>-cymene} and [Cp*MCl₂]₂ (M = Rh, Ir) afforded a series of cationic half-sandwich complexes, [(arene/Cp*)MCl{<i>κ</i>²-(<i>NE</i>)-EPPh₂Py)}]⁺. Reaction of O=PPh₂Py with precursors yielded known complexes [(arene/Cp*)MCl{<i>κ</i>²-(<i>PN</i>)-PPh₂Py)}]⁺ instead of expected complexes [(arene/Cp*)MCl{<i>κ</i>²-(<i>NO</i>)-O=PPh₂Py)}]⁺. All new complexes were isolated as counterion and characterized by spectroscopic techniques like FT-IR, NMR, mass, and UV–vis. Some representative complexes were structurally determined by X-ray crystallographic analysis, revealing typical three-legged piano stool geometry around the metal center with a five-membered metallacycle.</p>