A new divalent organoeuropium(II) fluoride and serendipitous discovery of an alkoxide complex from pentaphenylcyclopentadiene precursors

From the redox-transmetallation protolysis (RTP) reaction of europium metal, Hg(C₆F₅)₂ and pentaphenylcyclopentadiene, we isolated and crystallographically characterised small amounts of the first divalent europium fluoride half-sandwich complex [Eu(C₅Ph₅)(μ-F)(thf)₂]₂ (1). Subsequently, a rational synthesis of this complex from in situ formed [EuF₂(thf)n] and [Eu(C₅Ph₅)₂] was carried out. In addition, the new divalent Eu alkoxide complex [Eu(OC₅Ph₅∗)₂(thf)₄] (2) (OC₅Ph₅∗ = 2,3,4,5,5 pentaphenylcyclopenta-1,3-dienolate) was identified by X-ray diffraction analysis, in which an intriguing phenyl group migration in the cyclopentadiene ligand occurred. This complex was shown to be derived from small impurities of 1,2,3,4,5-pentaphenylcyclopenta-1,3-dienol (C₅Ph₅OH) in the C₅Ph₅H starting material and was then synthesised on a larger scale. Density functional theory calculations provided evidence for the facile phenyl group migration observed in the cyclopentadienolate ring.

Australian Journal of Chemistry

Australian Journal of Chemistry

75

1445-0038

N/A

8 & 9

8