The Synthesis and Characterization of Phosphonium Indenylide Complexes of Ruthenium(II)

Abstract

Phosphonium indenylides (PHIN) are a promising, yet relatively unexplored class of transition metal ligands. The ylidic resonance structure b of this compound is isoelectronic with the cyclopentadienyl ligand which is ubiquitous throughout organometallic chemistry. Phosphonium indenylides have been found to have electron donating properties between those of η6-benzene and η5-cyclopentadienyl ligands and are tuneable based on the nature of the phosphine used. In addition, upon coordination, phosphonium indenylides exhibit planar chirality. These properties may potentially lead to interesting coordination chemistry and applications in catalysis.The phosphonium indenylides 1-C9H6PPh3 (I), 1-C9H6PMePh2 (II) and1-C9H6PMe2Ph (III) have been synthesized and reacted with [CpRu(MeCN)3]PF6 to form complexes of the type [CpRu(I-III)]PF6 (V-VII) which were characterized by NMR spectroscopy, ESI MS and X-ray crystallography. In an attempt to synthesize Ru-PHIN complexes with labile ligands attached to the metal centre, an arene exchange reaction between a PHIN ligand and RuCl2(η6-ethylbenzoate)(PPh3) was employed to produce RuCl2(II)(PPh3) which was characterized by extensive NMR spectroscopy.