Study of $\boldsymbol{\eta}^{\bf 6}$ - cyclic $\boldsymbol{\pi} $ -perimeter hydrocarbon ruthenium complexes bearing functionalized pyridyl diketones: Isolation of complexes with $\boldsymbol{\kappa}^\textbf{2}$ -N∩O and $\boldsymbol{\kappa}^\textbf{4}$ -N∩O bonding modes of ligands

Abstract

Chelating mono- and di-pyridyl functionalized β-diketones, viz. 1-phenyl-3-(2-pyridyl) propane-1,3-dione (pppdH) and 1,3-di(2-pyridyl)propane-1,3-dione (dppdH) ligands yielded new water soluble η6-arene ruthenium(II) complexes of the formulation [(η6-arene)Ru(κ2-N-O-pppdH)Cl] + (arene = C6H6 1, p-iPrC6H4Me 2, C6Me6 3) and [(η6-arene)2Ru2(κ4-N-O-dppd)Cl2] + (arene = C6H6 4, p-iPrC6H4Me 5, C6Me6 6), as their (complexes 1–4, 6) PF6 salt or (complex 5) BF4 salt. The complexes were obtained by treatment of respective precursors, [(η6-arene)Ru(μ-Cl)Cl]2 (arene = C6H6, p-iPrC6H4Me, C6Me6) in 1:2 and 1:1 molar ratio with pppdH and dppdH in the presence of NH4PF6/NH4BF4. All the complexes have been characterized on the basis of FT-IR and NMR spectroscopic data as well as by elemental analysis. Molecular structures of representative complexes 2, 5 and 6 have been confirmed by single crystal X-ray diffraction studies. The ‘O–C–C–C–O’ fragment of the coordinated ligand (pppdH) is neutral in complexes 1–3 and that of the dppdH ligand existed as a neutral as well as concomitantly uninegative fashion in complexes 4–6 due to the delocalization of π-electrons. Monomeric and dimeric areneruthenium complexes bearing ligands, 1-phenyl-3-(2-pyridyl)propane-1,3-dione (pppdH) and 1,3-di(2-pyridyl)propane-1,3-dione (dppdH) with κ 2-N∩O and κ 4-N∩O binding modes have been isolated and their structures elucidated.