A modular synthetic route has been developed to prepare a new series of cationic ruthenium (II) complexes with electron-withdrawing 1, 2-diacylcyclopentadienyl ligands. The 2-acyl-6-hydroxyfulvenes were synthesized from cyclopentadienide and acyl chlorides and converted to Tl (I) cyclopentadienyl salts using Tl2SO4/KOH. Transmetalation with Ru (η6-p-cymene) (μ-Cl) Cl2 followed by PF6− metathesis gives the complexes Ruη5-1, 2-C5H3 (CO–R) 2 (η6-p-cymene) PF6 (R = t-Bu, p-Tol, p-ClC6H4, p-IC6H4) in moderate to high yields. The new compounds were characterized by NMR and IR spectroscopy; mass spectrometry and elemental analysis were performed where applicable. X-ray analysis of one of the complexes confirms that electron-deficient Cp ligands retain η5-coordination and structural planarity within Ru (II) –arene sandwich architectures, highlighting their potential utility in electronically tunable organometallic frameworks.
Pokharel et al. (Sun,) studied this question.