A direct and practical approach for the synthesis of N-heterocyclic carbene coinage metal complexes

Zhu, Shifa; Liang, Ren‐Xiao; Jiang, Huanfeng

doi:10.1016/j.tet.2012.07.009

Cited by 54 publications

(37 citation statements)

References 37 publications

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“…16,35 Anal. Calcd for C 42 H 48 CuF 6 N 4 P: C,61.72;H,5.92;N,6.85. Found: C,61.56;H,5.82;N,6.97. [(SIMes) 2 Cu]PF 6 , 2i.…”

Section: General Synthetic Procedures For [(Nhc) 2 Cu]pfmentioning

confidence: 99%

Simple synthesis of neutral and cationic Cu-NHC complexes

Liu

et al. 2015

Dalton Trans.

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A direct and practical synthetic route to N-heterocyclic carbene copper complexes of [(NHC)CuX] (X = halide) and [(NHC)2Cu]PF6 types using commercially available copper powder is described. A number of copper-NHC complexes have been obtained in a range of yields from 26 to 99%. The reactions take place in air without removal of moisture and oxygen, and the excess of copper powder can be easily removed via simple filtration after completion. The direct reactions of imidazolium salts and copper powder can also be performed in aqueous media avoiding tedious purification processes. The procedure is also suitable for gram-scale preparation.

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“…16,35 Anal. Calcd for C 42 H 48 CuF 6 N 4 P: C,61.72;H,5.92;N,6.85. Found: C,61.56;H,5.82;N,6.97. [(SIMes) 2 Cu]PF 6 , 2i.…”

Section: General Synthetic Procedures For [(Nhc) 2 Cu]pfmentioning

confidence: 99%

Simple synthesis of neutral and cationic Cu-NHC complexes

Liu

et al. 2015

Dalton Trans.

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“…The first NHC silver(I) complex was prepared by Arduengo et al by reaction between a free carbene and silver(I) triflate [10]. Today, the reaction of imidazol(in)ium salts with a variety of silver(I) precursors such as Ag 2 O [11], Ag(OAc) [12,13], Ag 2 CO 3 [14] or AgCl [15], with K 2 CO 3 or Na 2 CO 3 as external base, allows for the formation of Ag(I)eNHC complexes in high yields. Ag(I)eNHC complexes are stable towards air and moisture.…”

Section: Introductionmentioning

confidence: 99%

Silver(I) and copper(I) complexes with bis-NHC ligands: Dinuclear complexes, cubanes and coordination polymers

Charra

Frémont

Breuil

et al. 2015

Journal of Organometallic Chemistry

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a b s t r a c tSilver(I) and copper(I) complexes containing neutral bis(N-heterocyclic carbene) (NHC) ligands and coordinated or non-coordinated chloride, bromide, iodide, or tetrafluoroborate anions, were synthesised. The nature of the anions impacts deeply the structural features of the complexes in the solid-state and neutral cubane-, neutral coordination polymer-, or dicationic bridged-type architectures have been characterised. The structures of (1,3-bis(3 0 -butylimidazol-2 0 -ylidene)benzene)disilver(I) dichloride (2a), bis(m-1,3-bis(3 0 -butylimidazol-2 0 -ylidene)benzene-k-C)tetra-m 3 -bromotetrasilver(I) (2b), bis(1,3-bis(3 0 -butylimidazol-2 0 -ylidene)benzene)disilver(I) tetrafluoroborate (2d) in 2d$CH 2 Cl 2 , (1,3-bis(3 0 -butylimidazol-2 0 -ylidene)benzene)dicopper(I) dichloride (3a) and (1,3-bis(3 0 -butylimidazol-2 0 -ylidene)benzene) dicopper(I) dibromide (3b) were established by X-ray diffraction. IntroductionSince the first stable free N-heterocyclic carbene (NHC) was isolated by Arduengo in 1991 [1], this class of ligands has found numerous applications in organometallic chemistry in particular for the preparation of new metal-based catalysts [2e9]. The first NHC silver(I) complex was prepared by Arduengo et al. by reaction between a free carbene and silver(I) triflate [10]. Today, the reaction of imidazol(in)ium salts with a variety of silver(I) precursors such as Ag 2 O [11], Ag(OAc) [12,13], Ag 2 CO 3 [14] or AgCl [15], with K 2 CO 3 or Na 2 CO 3 as external base, allows for the formation of Ag(I)eNHC complexes in high yields. Ag(I)eNHC complexes are stable towards air and moisture. The reaction of Ag 2 O with halide imidazol(in)ium salts, first described in 1998 by Lin, is particularly efficient to synthesise halide Ag(I)eNHC complexes under mild conditions, without having to handle free NHCs [11]. The second product formed following Lin's protocol being water, non-distilled solvents can be employed, which renders this approach very convenient and popular [11]. Ag(I)eNHC complexes are potent catalysts for e.g. the cycloaddition of CO 2 to terminal epoxides [16] and CeN coupling reactions [17]. During pharmacological studies, they proved to release in vivo slowly and steadily free silver cations acting as tumour cell killers or suppressants of infections [18e21]. Ag(I)e NHCs are mostly employed as transmetalating agents to access late transition metal NHC complexes, without the need to handle unwieldy free carbenes. They are indeed known to transmetalate efficiently their NHC ligand(s) to Cu [22], Ni [23,24] Pd [23,25], Pt [25] and Au [26,27] precursors. The coordination geometry around the Ag(I) centre tends to be linear. When the associated anion (X À ) is a halide, the formation of polynuclear complexes or clusters with XeAgeX bridge(s) can lead to a broad structural diversity in the solid-state. In Ag(I)eNHC clusters complexes, d 10 ed 10 interactions are often encountered [28,29], while the coordination geometry around the Ag(I) cations may deviate from linear to trigonal or even tetr...

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“…The solvents used were purified, degassed, and dried according to standard purification techniques [49] or obtained from an MBraun solvent purification system. Complexes 1, 2 [24] and [PdCl 2 (IMes) 2 ] (IMes = 1,3-bis(mesityl)-imidazol-2-ylidene) [50] were obtained according to literature procedures. All further chemicals were purchased from commercial sources and used as received.…”

Section: Methodsmentioning

confidence: 99%