Syntheses and Electrochemical Properties of [C5Me5Ru]+ Complexes with Polycyclic Arenes. Crystal Structure of[(C5Me5)Ru( μ6-chrysene)]PF6 · 0.5 Me2CO

Abstract

Mononuclear and binuclear compounds [(C5Me5)Ru(η6-arene)PF6 and [(C5Me5Ru)2(η6,η6-arene)](PF6)2 were prepared by reacting (C5Me5)RuCl2, the arene and silver acetate with subsequent addition of NH4PF6, for arene = phenanthrene, chrysene, triphenylene, fluorene, bifluorene, biphenyl and 4,4′-biphenyl. The mononuclear compounds were also prepared for arene = naphthalene, anthracene, pyrene and coronene. The 1H and 13C NMR spectra are reported. By cyclic voltammetry all compounds show a first reduction potential that is considerably more positive compared with the free arene. The first cathodic wave is irreversible for a wide range of scanning speeds. However, the mononuclear coronene and the binuclear phenanthrene compounds show reversibility. The crystal structure of [(C5Me5)Ru(η6-chrysene)]PF6·0.5 Me2CO was determined by X-ray diffraction (3797 unique observed reflexions, R = 0.098). Crystal data: a = 1689.2(2), b = 1524.0(8), c = 2263.5(3) pm, β= 107.22(1)°, space group P21/n, Ζ = 8. Crystallographically independent, two cations [(C5Me5)Ru(η6-chrysene)]+ and two anions PF6 - are present, but their structures are essentially equal. The [C5Me5Ru]+ unit is bonded to one of the terminal benzene rings of the chrysene in a sandwich manner; the rings bonded to Ru are nearly coplanar. The PF6 - ions and the C5Me5 rings exhibit strong thermal vibrations.