Ligand Exchange at a Gold(I) Carbene Complex

Jahnke, Mareike C.; Pape, Tania; Hahn, F. Ekkehardt

doi:10.5560/znb.2013-3076

Cited by 7 publications

(7 citation statements)

References 30 publications

(37 reference statements)

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“…These observations are in accord with NMR data recorded for a related digold complex bearing a bridging picolyl-substituted imidazolin-2-ylidene ligand. [25] Furthermore, substitution of the chlorido ligand in [4] for a pyridine donor led to an upfield shift of the resonance of the C NHC atom of the benzimidazolin-2-ylidene ligand from δ = 180.8 ppm for [4] to δ = 175.9 for [5](BF 4 ) 2 in good agreement with other cationic gold(I) complexes bearing a benzimidazolin-2-ylidene and a pyridine [26] or a pyridine derived [27] coligand bound to gold(I). [27]…”

Section: Resultssupporting

confidence: 79%

Synthesis of NHC Complexes with an N‐(2‐Oxopropyl) Group

Hervé

Jahnke

Hahn

2021

Zeitschrift anorg allge chemie

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Dedicated to Prof. Wolfgang Kaim on the Occasion of his 70th BirthdayThe unsymmetrically N,N ,N'-picolylbenzimidazolium chloride (H-1)Cl, featuring an N-protecting group has been prepared. Reaction of (H-1)Cl with Ag 2 O followed by transmetallation of the NHC to [MCl 2 (Cp*)] 2 (M = Rh, Ir) yielded complexes [MCl(Cp*)(k 2 -1)]Cl (M = Rh, [2]Cl; M = Ir, [3]Cl) with a chelating coordinated C NHĈ N pyridine ligand. Anion exchange gave complexes [2]BF 4 (M = Rh) and [3]BF 4 (M = Ir). Transmetallation of the NHC ligand from silver(I) to gold(I) gave the mononuclear complex [AuCl(1)] [4] bearing a monodentate, N-picoly funtionalized NHC ligand. Complex [4] reacts with AgBF 4 to yield the dinuclear complex [5](BF 4 ) 2 featuring two bridging μ 2 -C NHC^Npyridine ligands. The molecular structures of [2]BF 4 • CH 2 Cl 2 and [3]BF 4 • CH 2 Cl 2 have been determined by X-ray diffraction studies.

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Section: Resultssupporting

confidence: 79%

Synthesis of NHC Complexes with an N‐(2‐Oxopropyl) Group

Hervé

Jahnke

Hahn

2021

Zeitschrift anorg allge chemie

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“…Ligand exchange reactions of metal complexes are a phenomenon with increasing interest in the scientific community. − It is well known that rhodium, ruthenium, platinum, and gold complexes suffer ligand replacement reactions. ,, For instance, cisplatin has to hydrolyze to reactive aqua species − prior to binding to its targets. ,− Additionally, ligand exchange is used to coordinate metallodrugs, e.g., gold complexes, to carrier ligands for high accumulation within cells. ,− …”

Section: Introductionmentioning

confidence: 99%

“…Gold(I) complexes are also susceptible to undergo rearrangement reactions. ,− Ligands can be categorized as carrier ligands or leaving groups, depending on their binding strength to the metal. Suitable carriers represent N -heterocyclic carbenes (NHCs).…”

Section: Introductionmentioning

confidence: 99%

Internal and External Influences on Stability and Ligand Exchange Reactions in Bromido[3-ethyl-4-aryl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) Complexes

et al. 2021

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The ligand scrambling reaction of gold(I) complexes is a phenomenon occurring primarily in L–Au I –X (L = phosphine, N -heterocyclic carbene (NHC), and thiol; X = halide and thiol) complexes and has been observed among others for e.g., the bromido[3-ethyl-4-(4-methoxyphenyl)-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2 H -imidazol-2-ylidene]gold(I) complex ( 7a ), which underwent ligand rearrangement in aqueous solutions. In this study, we investigated the influence of substituents on the 4-aryl ring of the related (NHC)Au I Br complexes ( 1a – 9a ) in terms of the conversion to the [(NHC) 2 Au I ] + ( 1b – 9b ) and [(NHC) 2 Au III Br 2 ] + ( 1c – 9c ) species. Furthermore, the influence of external factors such as solvent, temperature, concentration, and presence of halides (Cl – , Br – , and I – ) or hydroxyl ions was studied to gain a deeper understanding of the ligand rearrangement reaction. The substituent on the 4-aryl ring has a marginal impact on the scrambling reaction. Out of the investigated organic solvents (dimethylformamide (DMF), dimethyl sulfoxide (DMSO), ethanol (EtOH), methanol (MeOH), and acetonitrile (ACN)), only ACN separates single complex molecules. In all other solvents, relatively stable ((NHC)Au I Br) 2 dimers are present. The addition of water to ACN solutions forces the formation of such dimeric units, starting the transformation to [(NHC) 2 Au I ] + and [(NHC) 2 Au III Br 2 ] + . The rate-determining step is the release of Br – from a T-shape intermediate because an excess of KBr terminates this reaction. Furthermore, it is obvious that only single molecules react with halides. The aurophilic interactions between two (NHC)Au I Br molecules are too strong in the presence of water and largely impeded reaction with halides. As a single molecule, the reaction with Cl – (e.g., in a 0.9% NaCl solution) is notable, while I – even leads to a fast and quantitative conversion to (NHC)Au I I and finally to [(NHC) 2 Au I ] + .

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“…[32] Compound [(4)AuI] is characterized by an excellent fluorescence quantum yield of F=0.70. However, the coordination of a highly electron-rich thiolato ligand instead of the halogen ligand should lead to a significant increase of the electron density at gold.…”

Section: Carbon Monoxidementioning

confidence: 99%

Metal Complexes of a Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC) as Luminescent Carbon Monoxide Chemodosimeters

Kos

Plenio

2014

Chemistry A European J

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Several metal complexes with a boron dipyrromethene (BODIPY)-functionalized N-heterocyclic carbene (NHC) ligand 4 were synthesized. The fluorescence in [(4)(SIMes)RuCl2(ind)] complex is quenched (Φ = 0.003), it is weak in [(4)PdI2(Clpy)] (Φ = 0.033), and strong in [(4)AuI] (Φ = 0.70). The BODIPY-tagged complexes can experience pronounced changes in the brightness of the fluorophore upon ligand-exchange and ligand-dissociation reactions. Complexes [(4)MX(1,5-cyclooctadiene)] (M = Rh, Ir; X = Cl, I; Φ = 0.008-0.016) are converted into strongly fluorescent complexes [(4)MX(CO)2] (Φ = 0.53-0.70) upon reaction with carbon monoxide. The unquenching of the Rh and Ir complexes appears to be a consequence of the decreased electron density at Rh or Ir in the carbonyl complexes. In contrast, the substitution of an iodo ligand in [(4)AuI] by an electron-rich thiolate decreases the brightness of the BODIPY fluorophore, rendering the BODIPY as a highly sensitive probe for changes in the coordination sphere of the transition metal.

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Ligand Exchange at a Gold(I) Carbene Complex

Cited by 7 publications

References 30 publications

Synthesis of NHC Complexes with an N‐(2‐Oxopropyl) Group

Synthesis of NHC Complexes with an N‐(2‐Oxopropyl) Group

Internal and External Influences on Stability and Ligand Exchange Reactions in Bromido[3-ethyl-4-aryl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) Complexes

Metal Complexes of a Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC) as Luminescent Carbon Monoxide Chemodosimeters

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