Synthesis, X-ray structure, and nuclear magnetic resonance (1H and 13C) studies of ruthenium(II) complexes containing pyrazolyl ligands

Abstract

The synthesis and n.m.r. spectra (¹H and ¹³C) are reported for 24 p-cymeneruthenium complexes belonging to one of the following families: [Ru(MeC₆H₄Prⁱ-p)(acac)X](3)–(9), [Ru(MeC₆H₄Prⁱ-p)(acac)L]BF₄(10)–(17), [Ru(MeC₆H₄Prⁱ-p)ClL₂]BF₄(19)–(22), and [Ru(MeC₆H₄Prⁱ-p)L₃][BF₄]₂(23), [Ru(MeC₆H₄Prⁱ-p)XL₂]BF₄(24), and [Ru(MeC₆H₄Prⁱ-p)X₂L](25), where X = Br, I, N₃, pz, mpz, dmpz, or idz, and L = pyridine, PPh₃, CNBu^t, P(OMe)₃, Hpz (pyrazole), Hmpz (3-methylpyrazole), Hdmpz (3,5-dimethylpyrazole), and Hidz (indazole) for complexes (3)–(17), and only azoles (pyrazoles and indazole) for the remaining ones. Crystals of [Ru(MeC₆H₄Prⁱ-p)(pz)(Hpz)₂]BF₄ are monoclinic, space group P2₁/c, with a= 9.882 6(2), b= 13.966 3(3), c= 31.690 2(15)Å, β= 94.650(3)°, and Z= 8. The structure was determined by X-ray diffraction and refined to R= 0.045 (R′= 0.036). There are two crystallographic units, each having an intramolecular hydrogen bond between a pyrazole and a pyrazolate ring, and another between the other pyrazole ligand and the BF₄ anion. The n.m.r. data (δ and J) of the azole complexes were carefully determined and are thoroughly discussed.