Stable Mono- and Dinuclear Organosilver Complexes

Abstract

A series of mononuclear and dinuclear complexes of silver(I), supported by an N-heterocyclic carbene and bound to sp 3 -, sp 2 -, and sp-hybridized carbanions, has been synthesized. Synthetic routes include transmetalation from organozinc, organomagnesium, and organosilicon reagents, as well as the deprotonation of a terminal alkyne. These complexes exhibit greater thermal stability than typical organosilver reagents, permitting spectroscopic and structural characterization. The carbanion-bridged disilver cations feature three-center, two-electron bonding with short Ag•••Ag distances. A mononuclear vinylsilver complex releases organic homocoupling products upon thermal decomposition, while mononuclear alkylsilver complexes exhibit nucleophilic behavior, for example, inserting CO 2 to form silver carboxylates.

The Effect of β‐Hydrogen Atoms on Iron Speciation in Cross‐Couplings with Simple Iron Salts and Alkyl Grignard Reagents

“…As econd structure with ethyl ligands bridging Cr centers,[ ((t-Bu)NP-(Ph) 2 N(t-Bu))Cr(m-Et)] 2 , [9] however shows amoderate degree of asymmetry in the methylene carbon atoms with respect to the metal centers,w hile the methyl carbon atoms are highly asymmetric to the extent that one Cr···C(methyl) distance for each metal is only approximately 0.5 greater than the sum of the covalent radii of the individual atoms. [10] Thefinal two reports show acation, {[(SIPr)Ag] 2 (m-Et)} + ,that has ahighly symmetric ethyl bridge [11] and an anion, {[Et 2 Zn] 2 (m-Et)} À , whose disordered metal centers prevented detailed discussion of bond lengths and angles. [12] Fors imple ferric salt cross-couplings with alkyl Grignard reagents,t he addition of NMP as ac o-solvent leads to significantly improved cross-coupling yields with b-hydrogencontaining alkyl Grignard reagents.…”

New Vistas in Transmetalation with Discrete “AgCF3” Species: Implications in Pd‐Mediated Trifluoromethylation Reactions

“…Before exploring the CF 3 group transfer from Ag to (dppp)Pd(Ph)I, we establisheda satouchstone the trifluorome-thylationof1 with the widelyu sed nucleophilic trifluoromethyl sourcesR 3 SiCF 3 (R=Me, [9] Et [4b,h,i] )i nc ombination with CsF.A fter 30 minutes, we only observed 2 in 19 %a nd traces using Me 3 SiCF 3 and Et 3 SiCF 3 ,r espectively (Figure 2a). [10] With these results as ar eference, we then focused on the activity of the scarce examples of isolated trifluoromethylsilver(I)c ompounds reportedi nt he literature to date:S IPrAgCF 3 [11] [SIPr = bis(1,3bis(2,6-diisopropylphenyl)imidazol-2-ylidene)] and (bathophenanthroline)Ag(CF 3 ). [12] The treatment of (dppp)Pd(Ph)I with 1.5 equiv of SIPrAgCF 3 (3) [13] resulted in < 5% yield of (dppp)Pd(Ph)(CF 3 )a fter 30 minutes (Figure 2a).…”

Synthesis of stable polymetalated aromatic complexes through metal–macrocycle capsule-triggered cyclization

“…Previous studies have proved that organosilver complexes have limited stability. 26 However, complexes 2a–2e are quite stable upon exposure to air and moisture. Preliminary reactivity studies revealed that reaction of 2a with CF 3 COOD gave rise to 2,3-deuterated indole in high yield, suggesting the nucleophilic nature of the Ag–C bonds.…”