Synthesis and Structural Characterization of <i>N</i>-Heterocyclic Carbene Gold(I) Complexes

Frémont, Pierre de; Scott, Natalie M.; Stevens, and Edwin D.; Nolan, Steven P.

doi:10.1021/om050111c

Cited by 480 publications

(428 citation statements)

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“…The average Au1-C1 and Au1-Cl1 bond lengths of 1.985(9) Å and 2.289(2) Å respectively are comparable to those reported for other Au(I)-NHC complexes. 48,[62][63][64] The average C1-Au1-Cl1 bond angle of figure 4 and was found to be similar to that of the recently described 65 …”

Section: A C C E P T E D Accepted Manuscriptsupporting

confidence: 82%

“…Finally, transmetallation from Ag(I)-NHC complexes to a gold(I) centre was effected by reaction of these complexes with ClAu(THT) 47 (where THT = tetrahydrothiophene), 48 and afforded analytically pure samples of 11 and 12 after a single recrystallisation from CH 2 Cl 2 /hexane. The carbene complex 11 could also be prepared directly from either of the imidazolium salts 6 and 7 using the method recently reported by Zhu and coworkers.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

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Some insights into the gold-catalysed A 3 -coupling reaction

Price

Brisdon

Randall

et al. 2017

Journal of Organometallic Chemistry

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Abstract.A series of cyclometallated and functionalised NHC gold(I) and gold(III) complexes, many of which feature chiral ligands, and their application to A 3 -coupling reactions is presented. Gold(III) complexes were found to be particularly effective catalysts for the coupling in a range of solvents, however no asymmetric induction was obtained when using chiral gold complexes and the rate of product formation was found to be similar even when using different ligand systems. In-situ NMR analysis of these reactions indicates that decomposition of the catalyst occurs during the course of the reaction while TEM studies revealed the presence of gold nanoparticles in crude reaction mixtures. Taken together these data suggest that the gold nanoparticales, rather than the intact gold complexes, could be the catalytically active species, and if so this may have significant implications for other gold-catalysed systems.Dedicated to Dr. Mark Whiteley (an outstanding colleague) on his retirement from the School of Chemistry, University of Manchester.

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Section: A C C E P T E D Accepted Manuscriptsupporting

confidence: 82%

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Some insights into the gold-catalysed A 3 -coupling reaction

Price

Brisdon

Randall

et al. 2017

Journal of Organometallic Chemistry

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“…The gold complexes 1a-d were then cleanly prepared by stirring the free carbenes a-d overnight in darkness in THF with AuCl(SMe 2 ), the same procedure used for the corresponding NHC complexes [16]. After removing the solvent under vacuum and washing with hexanes, the * To whom correspondence should be addressed.…”

Section: Stable Carbenes; Carbene Complexes; Goldmentioning

confidence: 99%

Cyclic (alkyl)(amino)carbene gold(I) complexes: A synthetic and structural investigation

Frey

Dewhurst

Kousar

et al. 2008

Journal of Organometallic Chemistry

131

101

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A series of mono-and dicarbene gold(I) complexes of types Au(CAAC)(Cl) [CAAC = cyclic (alkyl) (amino)carbene] (1) and [Au(CAAC) 2 ] + [X] -(X = Cl, AuCl 2 ) (2) have been prepared through reaction of AuCl(SMe 2 ) with free carbenes a-e, and structurally characterized by single X-ray diffraction studies (1a, 1b, 2d, 2e). In addition two new free cyclic (alkyl)(amino)carbenes (c and e) have been synthesized. Keywords Stable Carbenes; Carbene Complexes; GoldFollowing the discovery of the first stable derivatives [1,2], singlet carbenes have received considerable attention as ligands for transition metals [3,4]. Carbenes feature a strong σ-donating ability, and strongly bind metal centers of high and low oxidation states [5]. Additionally, the possibility to tune their electronic and steric properties by variation of substituents [6], make carbenes versatile ligands for transition metal catalysts [7]. Since the Au(I) catalyzed asymmetric aldol reaction was published in the late 1980s [8], the use of Au (I) complexes in catalysis has received a lot of attention [9,10]. The first NHC substituted neutral and cationic gold(I) complexes were published in 1989 [11], and their application in catalysis stated in 2003 [12].We have already reported the synthesis and isolation of well-defined cyclic (alkyl)(amino) carbenes (CAAC) [13a], their use for the activation of small molecules [13b-d], their properties as ligand for transition metals [13e,f], and recently the preparation of a CAAC gold(I) complex, which allows for the catalytic formation of allenes, starting from enamines and alkynes [14]. This manuscript describes the synthesis and characterization of a series of Au(I) complexes, featuring one or two CAACs, depending on the bulkiness of the carbene ligand.The free carbenes (a-e) including the new ones (c and e) were readily prepared by deprotonation with LDA of the corresponding iminium salts; the latter were synthesized using the hydroiminiumation route [15] as shown in Scheme 1.The gold complexes 1a-d were then cleanly prepared by stirring the free carbenes a-d overnight in darkness in THF with AuCl(SMe 2 ), the same procedure used for the corresponding NHC complexes [16]. After removing the solvent under vacuum and washing with hexanes, the * To whom correspondence should be addressed. E-mail: gbertran@mail.ucr.edu Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Under the same reaction conditions, a different behavior was observed for carbene e. In this case the reaction of a stoichiometric amount of e with AuCl(SMe 2 ) did not afford the expected mono-carbene gold c...

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“…For example, Au(SIMes)Cl containingabulky SIMesligandwas showntobeefficient in mediating cycloisomerization of 1,5-enynes (SIMes =N ,N'-bis [2,4,6-(trimethyl)phenyl]imidazolidin-2-ylidene) [5].T he crystal structure of Au(SIMes)Cl(polymorph I) wasreported [6]. The present crystal structure is anew polymorph of this reported structure (polymorph II).…”

Section: Discussionmentioning

confidence: 55%