The cyclooctadiene ligand in [IrCl(COD)]2 is hydrogenated under transfer hydrogenation conditions: a study in the presence of PPh3 and a strong base in isopropanol

Abstract : The interaction of [IrCl(COD)]2 with PPh3 in isopropanol has been investigated for various P/Ir ratios, in the absence or presence of a strong base (KOtBu), at room temperature and at reflux. At room temperature, PPh3 adds to the metal center to yield [IrCl(COD)(PPh3)] and additional PPh3 only undergoes rapid degenerative ligand exchange. Subsequent addition of KOtBu affords [IrH(COD)(PPh3)2] as the main compound, even for high P/Ir ratios, although very minor amounts of products having a “HIr(PPh3)3” core are also generated. Warming to the solvent reflux temperature results in a rapid (< 1 h) and quantitative COD removal from the system as hydrogenated products (54.4% of cyclooctene plus 32.2% of cyclooctane according to a quantitative GC analysis) and in the eventual generation of [IrH3(PPh3)3]. The latter is observed as a mixture of the fac and mer isomers in solvent-dependent proportions. Other minor products, one of which is suggested to be mer-cis-[IrH2(OiPr)(PPh3)3] by the NMR characterization, are also generated. These results show that, contrary to certain previously published assumptions, systems of this kind are unlikely to function via a COD-containing active species in transfer hydrogenation catalyses conducted in hot isopropanol in the presence of a strong base.
Document type :
Journal articles
Complete list of metadatas

https://hal.archives-ouvertes.fr/hal-01455813
Contributor : Rinaldo Poli <>
Submitted on : Wednesday, February 8, 2017 - 12:40:18 PM
Last modification on : Friday, October 11, 2019 - 8:22:10 PM
Long-term archiving on : Tuesday, May 9, 2017 - 12:12:52 PM

Identifiers

Collections

Citation

S. M. Wahidur Rahaman, Jean-Claude Daran, Eric Manoury, Rinaldo Poli. The cyclooctadiene ligand in [IrCl(COD)]2 is hydrogenated under transfer hydrogenation conditions: a study in the presence of PPh3 and a strong base in isopropanol. Journal of Organometallic Chemistry, Elsevier, 2017, 829, pp.14-21. ⟨10.1016/j.jorganchem.2016.10.009⟩. ⟨hal-01455813⟩

Share

Metrics

Record views

248

Files downloads

290