Rational design of highly active "hybrid" phosphine-phosphinite pincer iridium catalysts for alkane metathesis

Agnieszka J. Nawara-Hultzsch; Jason D. Hackenberg; Benudhar Punji; Carolyn Supplee; Thomas J. Emge; Brad C. Bailey; Richard R. Schrock; Maurice Brookhart; Alan S. Goldman

doi:10.1021/cs400624c

Rational design of highly active "hybrid" phosphine-phosphinite pincer iridium catalysts for alkane metathesis

Agnieszka J. Nawara-Hultzsch, Jason D. Hackenberg, Benudhar Punji, Carolyn Supplee, Thomas J. Emge, Brad C. Bailey, Richard R. Schrock, Maurice Brookhart, Alan S. Goldman

Rutgers University

Research output: Contribution to journal › Article

41 Citations (Scopus)

Abstract

Both the bisphosphine and bisphosphinite pincer complexes ( ^tBu4PCP)IrH₂ and (^tBu4POCOP)IrH₂ can cocatalyze alkane metathesis in tandem with olefin metathesis catalysts, but the two complexes have different resting states during catalysis, suggesting that different steps are turnover-limiting in each case. This led to the hypothesis that a complex with intermediate properties would be catalytically more active than either of these two species. Accordingly, "hybrid" phosphine-phosphinite pincer ligands (PCOP) and the corresponding iridium complexes were synthesized (3c-e). In tandem with olefin-metathesis catalyst MoF12, (^tBu4PCOP)IrH₂ displays significantly higher activity for the metathesis of n-hexane than does (^tBu4PCP)IrH ₂ or (^tBu4POCOP)IrH₂. (^tBu2PCOP ^iPr2)IrH₄ (3d) is even more active (>30-fold more active than (^tBu4POCOP)IrH₂) and affords nearly 4.6 M alkane products after 8 h at 125 C.

Original language	English
Pages (from-to)	2505-2514
Number of pages	10
Journal	ACS Catalysis
Volume	3
Issue number	11
DOIs	https://doi.org/10.1021/cs400624c
Publication status	Published - Nov 1 2013

Keywords

alkane metathesis
dehydrogenation
homogeneous catalysis
iridium
pincer complexes

ASJC Scopus subject areas

Catalysis
Chemistry(all)

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10.1021/cs400624c

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Nawara-Hultzsch, A. J., Hackenberg, J. D., Punji, B., Supplee, C., Emge, T. J., Bailey, B. C., Schrock, R. R., Brookhart, M., & Goldman, A. S. (2013). Rational design of highly active "hybrid" phosphine-phosphinite pincer iridium catalysts for alkane metathesis. ACS Catalysis, 3(11), 2505-2514. https://doi.org/10.1021/cs400624c

Rational design of highly active "hybrid" phosphine-phosphinite pincer iridium catalysts for alkane metathesis. / Nawara-Hultzsch, Agnieszka J.; Hackenberg, Jason D.; Punji, Benudhar; Supplee, Carolyn; Emge, Thomas J.; Bailey, Brad C.; Schrock, Richard R.; Brookhart, Maurice; Goldman, Alan S.

In: ACS Catalysis, Vol. 3, No. 11, 01.11.2013, p. 2505-2514.

Research output: Contribution to journal › Article

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abstract = "Both the bisphosphine and bisphosphinite pincer complexes ( tBu4PCP)IrH2 and (tBu4POCOP)IrH2 can cocatalyze alkane metathesis in tandem with olefin metathesis catalysts, but the two complexes have different resting states during catalysis, suggesting that different steps are turnover-limiting in each case. This led to the hypothesis that a complex with intermediate properties would be catalytically more active than either of these two species. Accordingly, {"}hybrid{"} phosphine-phosphinite pincer ligands (PCOP) and the corresponding iridium complexes were synthesized (3c-e). In tandem with olefin-metathesis catalyst MoF12, (tBu4PCOP)IrH2 displays significantly higher activity for the metathesis of n-hexane than does (tBu4PCP)IrH 2 or (tBu4POCOP)IrH2. (tBu2PCOP iPr2)IrH4 (3d) is even more active (>30-fold more active than (tBu4POCOP)IrH2) and affords nearly 4.6 M alkane products after 8 h at 125 C.",

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