Study of novel η⁵-cyclopentadienyl and η⁶-arene platinum group metal complexes containing a N₄-type ligand and their structural characterization

The mononuclear η⁵-cyclopentadienyl complexes [(η⁵-C₅H₅)Ru(PPh₃)₂Cl], [(η</sup>5</sup>-C₅H₅)Os(PPh₃)₂Br] and pentamethylcyclopentadienyl complex [(η⁵-C₅Me₅)Ru(PPh₃)₂Cl] react in the presence of 1 eq. of the tetradentate <i>N,N′</i>-chelating ligand 3,5-bis(2-pyridyl)pyrazole (bpp-H) and 1 eq. of NH₄PF₆ in methanol to afford the mononuclear complexes [(η⁵-C₅H₅)Ru(PPh₃)(bpp-H)]PF₆ ([<b>1</b>]PF₆), [(η⁵-C₅H₅)Os(PPh₃)(bpp-H)]PF₆ ([<b>2</b>]PF₆) and [(η⁵-C₅Me₅)Ru(PPh₃)(bpp-H)]PF₆ ([<b>3</b>]PF₆), respectively. The dinuclear η⁵-pentamethylcyclopentadienyl complexes [(η⁵-C₅Me₅)Rh(μ-Cl)Cl]₂ and [(η⁵-C₅Me₅)Ir(μ-Cl)Cl]₂ as well as the dinuclear η⁶-arene ruthenium complexes [(η⁶-C₆H₆)Ru(μ-Cl)Cl]₂ and [(η⁶-<i>p</i>-ⁱPrC₆H₄Me)Ru(μ-Cl)Cl]₂ react with 2 eq. of bpp-H in the presence of NH₄PF₆ or NH₄BF₄ to afford the corresponding mononuclear complexes [(η⁵-C₅Me₅)Rh(bpp-H)Cl]PF₆ ([<b>4</b>]PF₆), [(η⁵-C₅Me₅)Ir(bpp-H)Cl]PF₆ ([<b>5</b>]PF₆), [(η⁶-C₆H₆)Ru(bpp-H)Cl]BF₄ ([<b>6</b>]BF₄) and [(η⁶-<i>p</i>-ⁱPrC₆H₄Me)Ru(bpp-H)Cl]BF₄ ([<b>7</b>]BF₄). However, in the presence of 1 eq. of bpp-H and NH₄BF₄ the reaction with the same η⁶-arene ruthenium complexes affords the dinuclear salts [(η⁶-C₆H₆)₂Ru₂ (bpp)Cl₂]BF₄ ([<b>8</b>]BF₄) and [(η⁶-<i>p</i>-ⁱPrC₆H₄Me)₂Ru₂ (bpp)Cl₂]BF₄ ([<b>9</b>]BF₄), respectively. These compounds have been characterized by IR, NMR and mass spectrometry, as well as by elemental analysis. The molecular structures of [<b>1</b>]PF₆, [<b>5</b>]PF₆ and [<b>8</b>]BF₄ have been established by single crystal X-ray diffraction studies and some representative complexes have been studied by UV–vis spectroscopy.