X-ray characterization of triphenylphosphine-gold(I) olefin π-complexes and the revision of their stability in solution

Motloch, Petr; Blahut, Jan; Cı́sařová, Ivana; Roithová, Jana

doi:10.1016/j.jorganchem.2017.07.011

“…[8,[17][18][19][20] An earlier theoretical analysis suggested that symmetrically bound alkene complexes are actually deactivated toward external nucleophiles and that slippage from an h 2 to h 1 coordination mode is crucial to activate the C = Cbond and facilitate orbital overlap in the transition state for nucleophilic attack. [21] Due to their relevance as potential catalytic intermediates,an umber of linear Au I alkene complexes have been isolated and structurally characterised, [22][23][24][25][26][27][28][29][30][31][32][33] as have related three-coordinate trigonal planar species. [34] In contrast, examples of crystallographically characterised linear Cu I and Ag I alkene complexes are extremely rare (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Group 11 Borataalkene Complexes: Models for Alkene Activation

Phillips

¹

,

Kong

²

,

White

³

et al. 2021

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A series of linear late transition metal (M=Cu, Ag, Au and Zn) complexes featuring a side‐on [B=C]− containing ligand have been isolated and characterised. The [B=C]− moiety is isoelectronic with the C=C system of an alkene. Comparison across the series shows that in the solid‐state, deviation between the η2 and η1 coordination mode occurs. A related zinc complex containing two [B=C]− ligands was prepared as a further point of comparison for the η1 coordination mode. The bonding in these new complexes has been interrogated by computational techniques (QTAIM, NBO, ETS‐NOCV) and rationalised in terms of the Dewar–Chatt–Duncanson model. The combined structural and computational data provide unique insight into catalytically relevant linear d10 complexes of Cu, Ag and Au. Slippage is proposed to play a key role in catalytic reactions of alkenes through disruption and polarisation of the π‐system. Through the preparation and analysis of a consistent series of group 11 complexes, we show that variation of the metal can impact the coordination mode and hence substrate activation.

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“…The gain in stabilization by additional o -biphenyl substitution was clearly evident by continuing the series; preparation of [Ph( o -biphenyl) 2 PAu(vinyl trimethylsilane)]SbF 6 proceeded cleanly with no special handling required. Recently, Roithová and co-workers showed that triphenylphosphine π-complexes could be prepared by utilizing low-temperature conditions and a high excess of alkene (100 equiv of 2-methyl-2-butene, −28 °C) . For 2d , the use of two biphenyl substituents allows more standard conditions to be used (ambient temperature and small excess of alkene; Scheme ).…”

Section: Resultsmentioning

confidence: 99%

“…Triphenylphosphine, the most traditionally used, is notorious for its propensity to decompose to (Ph 3 P) 2 Au + , the inactive byproduct of disproportionation. − Hammond, Xu, and co-workers showed that incorporation of a single o -biphenyl substituent (Ph 2 P( o -biphenyl) compared to Ph 3 P) increased the lifetime of cationic gold(I) in solution, while incorporation of a second o -biphenyl substituent led them to the development and commercialization of a precatalyst that displays exceptional stability and efficiency . Moving from these insights, we sought to examine the coordination and solution chemistry of π-complexes that would potentially share the advantageous electronic features of ligands lacking strong donor substituents, while benefiting from the stabilization provided by the o -biphenyl substituent.…”

Section: Introductionmentioning

confidence: 99%

Bisbiphenyl Phosphines: Structure and Synthesis of Gold(I) Alkene π-Complexes with Variable Phosphine Donicity and Enhanced Stability

Griebel

¹

,

Hodges

²

,

Yager

³

et al. 2020

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This paper describes the synthesis and characterization of RP(o-biphenyl)2 phosphine ligands (where R = PhO, Ph, and t-Bu), corresponding gold(I) chloride precatalysts, gold(I) triflate catalysts, and gold(I) π-complexes. All ligands and gold chlorides and three π-complexes were characterized in the solid state. The most significant differences between complexes in the solid state were varying P–Au bond lengths, a consistent reflection of the different electronic character of each phosphine. NMR spectroscopic data on enol ether π-complexes is consistent with increasing cationic character in the alkene fragment, from R = t-Bu to R = Ph and OPh. The intermolecular alkene exchange process for [LAu(methoxypropene)]SbF6 (L = PhO(o-biphenyl)2P) is faster than that of the analogous complex with t-Bu2(o-biphenyl)P, presumably due to the higher electrophilicity of the former complex. Examination of a series of vinyl silane π-complexes with triaryl phosphine ligands reveals increasing stability and ease of preparation (Ph3P < Ph2P(o-biphenyl) < PhP(o-biphenyl)2). These results reveal that incorporation of a second biphenyl substituent into ligand architectures allows preparation of a series of gold π-complexes with increased stability over a range of phosphine donicity.

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“…Due to their relevance as potential catalytic intermediates, a number of linear Au I alkene complexes have been isolated and structurally characterised, [22–33] as have related three‐coordinate trigonal planar species [34] . In contrast, examples of crystallographically characterised linear Cu I and Ag I alkene complexes are extremely rare (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Group 11 Borataalkene Complexes: Models for Alkene Activation

Phillips

¹

,

Kong

²

,

White

³

et al. 2021

View full text Add to dashboard Cite

A series of linear late transition metal (M=Cu, Ag, Au and Zn) complexes featuring a side‐on [B=C]− containing ligand have been isolated and characterised. The [B=C]− moiety is isoelectronic with the C=C system of an alkene. Comparison across the series shows that in the solid‐state, deviation between the η2 and η1 coordination mode occurs. A related zinc complex containing two [B=C]− ligands was prepared as a further point of comparison for the η1 coordination mode. The bonding in these new complexes has been interrogated by computational techniques (QTAIM, NBO, ETS‐NOCV) and rationalised in terms of the Dewar–Chatt–Duncanson model. The combined structural and computational data provide unique insight into catalytically relevant linear d10 complexes of Cu, Ag and Au. Slippage is proposed to play a key role in catalytic reactions of alkenes through disruption and polarisation of the π‐system. Through the preparation and analysis of a consistent series of group 11 complexes, we show that variation of the metal can impact the coordination mode and hence substrate activation.

show abstract

X-ray characterization of triphenylphosphine-gold(I) olefin π-complexes and the revision of their stability in solution

Cited by 10 publications

References 31 publications

Group 11 Borataalkene Complexes: Models for Alkene Activation

Group 11 Borataalkene Complexes: Models for Alkene Activation

Bisbiphenyl Phosphines: Structure and Synthesis of Gold(I) Alkene π-Complexes with Variable Phosphine Donicity and Enhanced Stability

Group 11 Borataalkene Complexes: Models for Alkene Activation

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