Cationic, linear Au(i) N-heterocyclic carbene complexes: synthesis, structure and anti-mitochondrial activity

Baker, Murray V.; Barnard, Peter J.; Berners‐Price, Susan J.; Brayshaw, Simon K.; Hickey, James L.; Skelton, Brian W.; White, Allan H.

doi:10.1039/b602560a

Cited by 251 publications

(211 citation statements)

References 39 publications

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“…Here again, the 13 C NMR signal for the carbene carbon of 2d appeared at lower field (251.2 ppm) than that observed for 1d (235.0 ppm). (Table 1), and are in agreement with the literature for gold(I) complexes [12,[20][21][22][23][24][25][26][27][28][29][30][31]. The Au-C carbene bond lengths in 1a (1.987(9) Å) and 1b (1.983(2) Å) are comparable with those found in substituted NHC gold(I) chloro complexes [12,[18][19][20][21][22][23], and suggest a single bond character, in good agreement with the strong σ-donor character of CAACs.…”

supporting

confidence: 80%

“…The Au-C carbene bond lengths in 1a (1.987(9) Å) and 1b (1.983(2) Å) are comparable with those found in substituted NHC gold(I) chloro complexes [12,[18][19][20][21][22][23], and suggest a single bond character, in good agreement with the strong σ-donor character of CAACs. The cationic complexes 2d and 2e have slightly longer Au-C carbene bond lengths [2.0321(11) and 2.033(4) Å, respectively] in the range observed for cationic dicarbene (NHC) gold(I) complexes [24][25][26][27][28][29][30][31]. For all four gold complexes (1a, 1b, 2d and 2e), no aurophilic interactions between the Au atoms were observed (>7.4 Å).…”

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confidence: 99%

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

Frey

Dewhurst

Kousar

et al. 2008

Journal of Organometallic Chemistry

128

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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supporting

confidence: 80%

mentioning

confidence: 99%

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

Frey

Dewhurst

Kousar

et al. 2008

Journal of Organometallic Chemistry

128

101

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“…The octanol-water partition coefficients for cisplatin and cisPtI 2 were determined by modification of the reported shake flask method. 28 Water (50 mL, distilled after Milli-Q purification) and n-octanol (50 mL) were shaken together for 72 h to allow saturation of both phases. Solution of the complexes were prepared in the aqueous phase (3 × 10 −3 M) and an equal volume of octanol was added.…”

Section: Methodsmentioning

confidence: 99%

cis-Pt I₂(NH₃)₂: a reappraisal

et al. 2015

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The investigation of cis-PtI 2 (NH 3 ) 2 , the diiodido analogue of cisplatin (cisPtI 2 hereafter), has been unjustly overlooked so far mainly because of old claims of pharmacological inactivity. Some recent -but still fragmentary -findings prompted us to reconsider more systematically the chemical and biological profile of cisPtI 2 in comparison with cisplatin. Its solution behaviour, interactions with DNA and cytotoxic properties versus selected cancer cell lines were thus extensively analysed through a variety of biophysical and computational methods. Notably, we found that cisPtI 2 is highly cytotoxic in vitro toward a few solid tumour cell lines and that its DNA platination pattern closely reproduces that of cisplatin; cisPtI 2 is also shown to completely overcome resistance to cisplatin in a platinum resistant cancer cell line. The differences in the biological actions of these two Pt complexes are most likely related to slight but meaningful differences in their solution behaviour and reactivity. Overall, a very encouraging and unexpected pharmacological profile emerges for cisPtI 2 with relevant implications both in terms of mechanistic knowledge and of prospective clinical application. An ab initio DFT study is also included to support the interpretation of the solution behaviour of cisPtI 2 under physiological and slightly acidic pH conditions.

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“…Conversely, the carbene complexes of gold(I) did not initially received much attention, but at present they undergo a remarkable development thanks to their versatility as catalysts, 7 luminescent devices, 8 and potential drugs. 9 Since the seventies, it was known that amines attack isocyanides coordinated to a transition metal to give the corresponding NAC carbene derivatives 10 (NAC = nitrogen acyclic carbene) and such a protocol has been used by Vicente, Espinet and co-workers in the synthesis of gold(I) NAC carbene derivatives. 11 On the basis of the described outcomes, we have programmed the synthesis of new mixed bis-carbene NHC, NAC derivatives, which might be employed in the olefin diboronation analogously to their homoleptic [Au(NHC) 2 ] þ complexes 12 or as active antibacterial agents.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Mechanism of Formation of Novel NHC−NAC Bis-Carbene Complexes of Gold(I)

et al. 2011

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Novel [Au(NHC)(DIC)]BF 4 complexes (NHC = SIMes, IMes, SIPr, IPr; DIC = 2,6-dimethylphenyl isocyanide) were synthesized and characterized. These substrates react with secondary amines at room temperature under mild experimental conditions to give new bis-carbene NHC-NAC derivatives. The reaction of formation of the latter complexes with piperidine, morpholine, and diethylamine was studied by NMR and UV-vis spectrometry, and a mechanism involving a concomitant attack of the amine at the metal center and at the coordinated isocyanide was proposed on the basis of a detailed kinetic study. The mechanistic network was completely resolved by means of an independent determination of the equilibrium constant of formation of the adduct [Au(NHC)-

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Cationic, linear Au(i) N-heterocyclic carbene complexes: synthesis, structure and anti-mitochondrial activity

Cited by 251 publications

References 39 publications

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

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

cis-Pt I₂(NH₃)₂: a reappraisal

Synthesis and Mechanism of Formation of Novel NHC−NAC Bis-Carbene Complexes of Gold(I)

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Cationic, linear Au(i) N-heterocyclic carbene complexes: synthesis, structure and anti-mitochondrial activity

Cited by 251 publications

References 39 publications

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

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

cis-Pt I2(NH3)2: a reappraisal

Synthesis and Mechanism of Formation of Novel NHC−NAC Bis-Carbene Complexes of Gold(I)

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cis-Pt I₂(NH₃)₂: a reappraisal