Synthesis, Structures, and Properties of the Phosphonium-1-indenylide (PHIN) Ligands 1-C₉H₆PPh₃, 1-C₉H₆PMePh₂, and 1-C₉H₆PMe₂Ph and of the Corresponding Ruthenium(II) Complexes [Ru(η⁵-C₅H₅)(η⁵-PHIN)]PF₆

Syntheses of the phosphonium-1-indenylide (PHIN) ligands triphenylphosphonium-1-indenylide (1-C₉H₆PPh₃, <b>I</b>), methyldiphenylphosphonium-1-indenylide (1-C₉H₆PMePh₂, <b>II</b>), and dimethylphenylphosphonium-1-indenylide (1-C₉H₆PMe₂Ph, <b>III</b>) are reported, as are syntheses of the corresponding planar chiral ruthenium­(II) complexes [Ru­(η⁵-C₅H₅)­(η⁵-1-C₉H₆PPh₃)]­PF₆ (<b>IV</b>), [Ru­(η⁵-C₅H₅)­(η⁵-1-C₉H₆PMePh₂)]­PF₆ (<b>V</b>), and [Ru­(η⁵-C₅H₅)­(η⁵-1-C₉H₆PMe₂Ph)]­PF₆ (<b>VI</b>). The ruthenium complexes have been characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy, by X-ray crystallography, and by extensive DFT calculations, which produce optimized geometries consistent with the crystallographic data. The PHIN–Ru bond strengths are calculated to be ∼20 kcal/mol greater than the corresponding benzene–Ru bond strength of [Ru­(η⁵-C₅H₅)­(η⁶-C₆H₆)]⁺ and are compatible with the observed configurational stability of the complexes. That interconversion of enantiomers via interfacial exchange of the η⁵-bound ligands does not occur is demonstrated by the observation of diastereotopic phenyl groups in the ¹H NMR spectrum of <b>V</b> and of diastereotopic methyl groups in the ¹H NMR spectrum of <b>VI