Functionalized arene–ruthenium(ii) complexes: dangling vs. tethering side chain

Abstract

The reactivity of compounds [RuCl₂(η⁶-C₆H₅OCH₂CH₂OH)(L)] (L = phosphine or phosphite) towards the chloride abstractor AgSbF₆ has been investigated. Thus, the treatment of the triphenylphosphite complex [RuCl₂(η⁶-C₆H₅OCH₂CH₂OH){P(OPh)₃}] with one equivalent of AgSbF₆ gave rise to the formation of the dinuclear dichloro-bridged species [{Ru(μ-Cl)(η⁶-C₆H₅OCH₂CH₂OH){P(OPh)₃}}₂]²⁺ as the hexafluoroantimonate salt. On the other hand, the triphenylphosphine analog [RuCl₂(η⁶-C₆H₅OCH₂CH₂OH)(PPh₃)] led, under the same experimental conditions, to the di-ruthenium derivative [{RuCl(η⁶-C₆H₅OCH₂CH₂OH)(PPh₃)}₂(μ-Cl)][SbF₆] containing only one Cl-bridge. In sharp contrast, treatment of precursors [RuCl₂(η⁶-C₆H₅CH₂CH₂CH₂OH)(L)] (L = P(OPh)₃, PPh₃, P(OEt)₃) with AgSbF₆ resulted in the clean formation of the tethered compounds [RuCl{η⁶:κ¹(O)-C₆H₅CH₂CH₂CH₂OH}(L)][SbF₆]. The differences in reactivity observed have been rationalized by theoretical calculations.