Half-sandwich η6-benzene Ru(II) complexes of pyridylpyrazole and pyridylimidazole ligands: Synthesis, spectra, and structure

New series of half-sandwich ruthenium(II) complexes supported by a group of bidentate pyridylpyrazole and pyridylimidazole ligands [(η6-C6H6)Ru(L2)Cl][PF6] (1), [(η6-C6H6)Ru(HL3)Cl][PF6] (2), [(η6-C6H6)Ru(L4)Cl][PF6] (3), and [(η6-C6H6)Ru(HL5)Cl][PF6] (4) [L2, 2-[3-(4-chlorophenyl)pyrazol-1-ylmethyl]pyridine; HL3, 3-(2-pyridyl)pyrazole; L4, 1-benzyl-[3-(2′-pyridyl)]pyrazole; HL5, 2-(1-imidazol-2-yl)pyridine] are reported. The molecular structures of 1–4 both in the solid state by X-ray crystallography and in solution using 1H NMR spectroscopy have been elucidated. Further, the crystal packing in the complexes is stabilized by C–H⋯X (X = Cl and π), N–H⋯Cl, and π–π interactions.

Graphical abstractSystematic comparative studies (X-ray and 1H NMR) have been made on “piano-stool” complexes of Ru(II) with bidentate ligands 2-[3-(4-chlorophenyl)pyrazol-1-ylmethyl]pyridine, 3-(2-pyridyl)pyrazole, 1-benzyl-[3-(2′-pyridyl)]pyrazole, and 2-(1-imidazol-2-yl)pyridine]. Structural studies reveal extensive non-covalent interactions.Figure optionsDownload full-size imageDownload as PowerPoint slide