Intramolecular hydroamination with rhodium (I) and iridium (I) complexes containing a phosphine - N-heterocyclic carbene ligand

Leslie D. Field, Barbara A. Messerle, Khuong Q. Vuong, Peter Turner

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169 Citations (Scopus)

Abstract

Cationic Rh(I) and Ir(I) complexes of the form [M(PC)(COD)]BPh4 (M = Rh (4), Ir (5); PC = 3-[2-(diphenylphosphino)ethyl]-l-methylimidazol-2-ylidene) were synthesized by the addition of 3-[2-(diphenylphosphino)ethyl]-l-methylimidazolium (3) to [M(μ-OEt)(COD)]2 (M = Rh, Ir; COD = 1,5-cyclooctadiene) in the presence of base. COD was successfully displaced from [Rh(PC)(COD)]BPh 4 (4) by addition of carbon monoxide to a methanol/hexane suspension to form [Rh(PC)(CO)2]BPh4 (6). The analogous addition of CO to the iridium compound 5 resulted in the formation of the five-coordinate Ir(I) complex [Ir(PC)(COD)-(CO)]BPh4 (7). The single-crystal X-ray structures of 4, 5, and 7 were determined. The metal centers of 4 and 5 are square planar, and the metal center of 7 is a distorted trigonal bipyramid. Complexes 4-7 are effective as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to 2-methyl-l-pyrroline. Complete conversion (>97%) of 4-pentyn-1-amine was observed using complexes 4-7 as catalysts, in both chloroform-d and tetrahydrofuran-ds. Reactions in chloroform-d in general exhibited higher turnover rates than reactions in tetrahydrofuran-d s.

Original languageEnglish
Pages (from-to)4241-4250
Number of pages10
JournalOrganometallics
Volume24
Issue number17
DOIs
Publication statusPublished - 15 Aug 2005
Externally publishedYes

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