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Download fileRing Slippage and Dissociation of Pentamethylcyclopentadienyl Ligand in an (η5‑Cp*)Ir Complex with a κ3‑O,C,O Tridentate Calix[4]arene Ligand under Mild Conditions
journal contribution
posted on 2018-06-12, 14:57 authored by Takuya Kuwabara, Ryogen Tezuka, Mikiya Ishikawa, Takuya Yamazaki, Shintaro Kodama, Youichi IshiiThe first examples
of κ3-O,C,O tridentate calix[4]arene transition-metal
complexes [Cp*M(p-tBucalix[4]arene(2−)-κ3-O,C,O)]
(M = Ir, Rh) that are stable both in the solid state and in solution
were synthesized. The reaction of the Ir complex with 2 equiv of xylyl
isocyanide afforded the (η1-Cp*)Ir(CNXy)2 complex in which the Cp* ligand is slipped from an η5 to an η1 fashion, although ring slippage of an
η5-Cp* ligand is very uncommon in comparison with
that of Cp. The reaction of the (η1-Cp*)Ir complex
with additional 1 equiv of isocyanide resulted in the liberation of
the Cp* ligand as Cp*H, which was confirmed by 1H NMR.
This study provides the first observation of stepwise dissociation
of a Cp* ligand from group 4–10 transition-metals via η1 coordination. This unique phenomenon seems to be facilitated
by flexible coordination of an OH group in the C-metalated
calix[4]arene ligand.
