Silver Acetylide Research Articles

One-pot synthesis of electroconducting graphene coated silver nanoparticles from silver acetylide

One-pot synthesis of electroconducting graphene coated silver nanoparticles from silver acetylide

Mechanistic Study on AgI-Catalyzed Oxidative Cross-Coupling/Cyclization between Terminal Alkynes and β-Enamino Esters under Base Conditions.

A combined computational and experimental study was performed to elucidate the mechanism of the AgI-catalyzed oxidative cross-coupling/cyclization of terminal alkynes with β-enamino esters. The results indicated a more favorable AgI/Ag0-catalyzed radical mechanism (than cationic mechanism) which involves three key stages: (i) the initiation of radical species, (ii) the cyclization, and (iii) the formal 1,2-H shift. Meanwhile, the AgI species was found to be the active initiator for the delocalized nitrogen radical species generation, and Ag2CO3 acts as an effective oxidant to initiate the β-enamino ester radical formation. Furthermore, it was shown that the silver acetylide is the key intermediate in the title reaction and that the coordination of solvent dimethyl sulfoxide (DMSO) regulates the electronic properties of the Ag center better as compared with base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), thereby enhancing the negative charge of the reaction sites and promoting the cyclization process. Finally, the DBU was revealed to play a key role in the final 1,2-H shift process through the formation of [DBU-H]+, acting as a proton shuttle to assist the proton migration process. The theoretical results provide key insights into the AgI/Ag0-catalyzed radical mechanism and guidelines for further development of Ag-catalyzed synthetic methods.

The Self-Assembly of [{Ag3(C≡CtBu)2}n]n+ Building Units into a Template-Free Cuboctahedron and Anion-Encapsulating Silver Cages.

We describe the controlled synthesis of silver acetylide clusters based on a simple polymeric [Ag3L2]+ (L = -C≡CtBu) building block. A linear one-dimensional polymeric structure shows alternating pyramidal motifs and is the basic repeating unit forming discrete molecular cages (pentamers [X⊂Ag15L10]4+ and hexamers [PF6⊂Ag18L12]5+) obtained by incorporating suitable templates. These motifs and a rare template-free cuboctahedral [Ag12L8]4+ cluster (tetramer) were crystallographically characterized.

OZM Ball Drop Impact Tester (BIT‐132) vs. BAM Standard Method – a Comparative Investigation

AbstractSafety, performance, cost efficient synthesis and toxicity are the most important aspects of modern explosives. Sensitivity measurements are performed in accordance with different protocols all around the world. Sometimes the BAM drop hammer does not accurately reflect the sensitivity of an energetic material, in particular the sensitivity of primary explosives. Therefore, we present here preliminary results obtained using the novel ball drop tester (BIT‐132), manufactured by OZM research, following MIL‐STD‐1751 A (method 1016). The ball drop impact sensitivity tester is a device in which a free‐falling steel ball is dropped onto an unconfined sample, and is expected to produce more realistic results than the currently commonly used BAM method. The results obtained using the probit analysis were compared to those from the BAM drop hammer and friction tester. The following sensitive explosives were investigated: HMTD, TATP, TAT, Tetrazene, MTX‐1, KDNBF, KDNP, K2DNABT, Lead Styphnate Monohydrate, DBX‐1, Nickel(II) Hydrazine Nitrate, Silver Acetylide, AgN3, Pb(N3)2 RD‐1333, AgCNO, and Hg(CNO)2.

N-Alkynylthio Phthalimide: A Shelf-Stable Alkynylthio Transfer Reagent for the Synthesis of Alkynyl Thioethers.

A new kind of electrophilic alkynylthiolating reagent, called N-alkynylthio phthalimide, is designed and synthesized herein. This electrophilic sulfenylating reagent can be easily prepared in three steps from commercially available phthalimide and corresponding silver acetylide. Furthermore, the N-alkynylthio phthalimides are demonstrated to be efficient alkynylthio transfer reagents that can react with various C-nucleophiles, including β-ketoesters, aryl boronic acids, and Grignard reagents to afford a diverse range of alkynyl thioethers under mild conditions.

DFT studies on the mechanism of Ag2 CO3 -catalyzed hydroazidation of unactivated terminal alkynes with TMS-N3 : An insight into the silver(I) activation mode.

Silver-mediated hydroazidation of unactivated alkynes has been developed as a new method for the synthesis of vinyl azides. Density functional theory calculations toward this reaction reveal that terminal alkynes with TMS-N3 participated hydroazidation proceed through HN3 formation, deprotonation and silver acetylides formation, nucleophilic addition, and protonation of terminal carbon by AgHCO3 . It is also found that water molecules and activation modes of Ag (I) have a significant influence on the title reaction mechanism. Initially, catalyst Ag2 CO3 coordinates preferentially with internal N atom of TMS-N3 to assist water as hydrogen source and proton-shuttle in facilitating HN3 formation. Then, the regioselective anti-addition of HN3 to triple bond of active silver-acetylide or ethynyl carbinols affords product vinyl azide via Ag-C σ-bond activation or Ag…C π-coordination activation modes, and the former one is more favorable. The origin of the difference regioselectivity is ascribed to the electronic and orbital effects of the reactive sites. Moreover, Ag2 CO3 is the critical catalyst, acting as activator, base, and stabilizer to promote the HN3 and vinyl azide formation. Water molecule plays an important role as proton shuttle to promote HN3 and key active silver acetylides formation, thus improving the yield of product. © 2017 Wiley Periodicals, Inc.

Two- and three-dimensional silver acetylide frameworks with high-nuclearity silver cluster building blocks assembled using a bifunctional (4-ethynylphenyl)diphenyl phosphine ligand

A bifunctional ligand precursor (4-ethynylphenyl)diphenyl phosphine was synthesized and used for constructing silver acetylide frameworks. Its reaction with Ag(I) in the presence of triethylamine afforded silver acetylide [AgL]n, in which L=Ph2P-C6H4-4-CC− could act as a bifunctional ligand bearing both phenylethynide and phosphine binding sites for Ag(I). Reactions of [AgL]n and AgCF3CO2 under different conditions gave four silver acetylides. They are [Ag18L8(CF3COO)6(HCO3)4(DMF)4]n (1, DMF=dimethylformamide), [Ag20L8(CF3COO)12(DMF)6]n (2), [Ag17L6(CF3COO)9(HCO3)2]n (3), and [Ag17L6(CF3COO)9.58(HCO3)1.42]n (4). Crystallographic studies revealed that complex 1 crystallized in the triclinic space group P1¯ with a=14.1252(9)Å, b=18.6012(12)Å, c=25.2137(17)Å, α=108.340(2)°, β=95.386(2)°, γ=95.535(2)°, V=6204.6(7)Å3, and Z=1. Complex 2 crystallized in the monoclinic space group C2/c with a=48.046(4)Å, b=14.1860(10)Å, c=34.943(2)Å, β=98.315(3)°, V=23,566(3)Å3, and Z=4. Complex 3 crystallized in the triclinic space group P1¯ with a=15.5690(7)Å, b=16.7707(8)Å, c=34.0810(16)Å, α=93.4040(10)°, β=100.3690(10)°, γ=94.8250(10)°, V=8697.1(7)Å3, and Z=2. Complex 4 crystallized in the triclinic space group P1¯ with a=15.5396(6)Å, b=16.7595(7)Å, c=34.0225(15)Å, α=93.8140(10)°, β=100.1000(10)°, γ=94.9770(10)°, V=8660.2(6)Å3, and Z=2. The presence of Ag(I)–ethynide, Ag(I)–P and Ag(I)–Ag(I) bonding interactions makes all four silver acetylides to have two- and three-dimensional framework structures with unusual high-nuclearity silver cluster building blocks.

TRANSFORMATIONS OF COTARNINE CHLORIDE BY THE ACTION OF SILVER ACETYLIDES AND ALKYNES

Three-component reactions of cotarnine chloride with silver acetylides and methyl propiolate or ethynyl methyl ketone in acetonitrile, as well as two-component reactions of 5-phenylethynyl-substituted tetrahydro[1,3]dioxolo[4,5- g ]isoquinoline with alkynes in various solvents were studied. Performing them in 2,2,2-trifluoroethanol as the solvent, 10-phenylethynyl-substituted tetrahydro[1,3]dioxolo[4,5- i ][3]benzazocines were obtained in good yields. Authors: Leonid G. Voskressensky, Alexander A. Titov, Reza Samavati, Tatiana N. Borisova, Elena A. Sorokina, Alexey V. Varlamov

Transformations of cotarnine chloride by the action of silver acetylides and alkynes

Three-component reactions of cotarnine chloride with silver acetylides and methyl propiolate or ethynyl methyl ketone in acetonitrile, as well as two-component reactions of 5-phenylethynyl-substituted tetrahydro[1,3]dioxolo[4,5-g]isoquinoline with alkynes in various solvents were studied. Performing them in 2,2,2-trifluoroethanol as the solvent, 10-phenylethynyl-substituted tetrahydro[1,3]dioxolo[4,5-i]-[3]benzazocines were obtained in good yields.

Arenediazonium salts as electrophiles for the oxidative addition of gold(i).

Arenediazonium salts generated in situ from anilines have been found for the first time to efficiently oxidize [AuCl(L)] (L = SMe2, PPh3) complexes in DMSO as a solvent, under thermal conditions. The structure of the [AuArCl2(L)] complexes formed has been confirmed by X-ray diffraction analyses. These complexes have been used as intermediates, in a one pot cross-coupling reaction of anilines with silver acetylides.

Light‐Stable Silver N‐Heterocyclic Carbene Catalysts for the Alkynylation of Ketones in Air

AbstractN‐Heterocyclic carbene (NHC) silver(I) complexes were employed efficiently in the alkynylation of ketones. These cationic complexes were highly active and efficient under mild conditions and in air without the need for an additive. The mechanism of this transformation was investigated. Experiments suggest that the formation of a silver acetylide key intermediate and the release of one ligand from the silver centre enable the transformation.

Soluble Silver Acetylide for the Construction and Structural Conversion of All-Alkynyl-Stabilized High-Nuclearity Homoleptic Silver Clusters

Silver acetylide complex [Ag(ArC≡C)]n (Ar = 3,5-di-tert-butylphenyl) with unprecedented high solubility in common organic solvents has been designed and synthesized. The high solubility is due to two bulky tert-butyl substituents on the phenyl ring. This feature is significant to construct and isolate single crystals of all-alkynyl-stabilized silver clusters, which are crucial to investigate the intrinsic binding interaction and coordination modes between Ag(I) and ethynide ligands. Crystallization of [Ag(ArC≡C)]n under various conditions resulted in three high-nuclearity homoleptic silver acetylide clusters, namely, [Ag21(ArC≡C)20](OH) (1), [Ag16(ArC≡C)16] (2), and [Ag15(ArC≡C)15] (3). Complex 1 has a [Ag21] cluster protected by twenty 3,5-di-tert-butyl-phenylethynide ligands. Complexes 2 and 3 have neutral [Ag16] and [Ag15] clusters, respectively. In addition to these homoleptic silver clusters, two new silver acetylides [Ag20(ArC≡C)16(CH3COO)4] (4) and [Ag22(ArC≡C)16(NO3)4(CH3CH2OH)4](OH)2 (5) were synthesized. The acetate and nitrate anions in these structures are more like counterions instead of acting as critical building blocks or templates for cluster assembly. These results illustrated the significance of 3,5-di-tert-butyl-phenylethynide ligands in the construction and stabilization of high-nuclearity silver clusters. Analysis of structures of 1–5 revealed several novel coordination modes between Ag(I) and ethynide ligands, which contributed considerably to our knowledge of Ag(I)–ethynide binding interactions.

A Robust Microfluidic Device for the Synthesis and Crystal Growth of Organometallic Polymers with Highly Organized Structures

A simple and robust microfluidic device was developed to synthesize organometallic polymers with highly organized structures. The device is compatible with organic solvents. Reactants are loaded into pairs of reservoirs connected by a 15 cm long microchannel prefilled with solvents, thus allowing long-term counter diffusion for self-assembly of organometallic polymers. The process can be monitored, and the resulting crystalline polymers are harvested without damage. The device was used to synthesize three insoluble silver acetylides as single crystals of X-ray diffraction quality. Importantly, for the first time, the single-crystal structure of silver phenylacetylide was determined. The reported approach may have wide applications, such as crystallization of membrane proteins, synthesis and crystal growth of organic, inorganic, and polymeric coordination compounds, whose single crystals cannot be obtained using traditional methods.

A Robust Microfluidic Device for the Synthesis and Crystal Growth of Organometallic Polymers with Highly Organized Structures

AbstractA simple and robust microfluidic device was developed to synthesize organometallic polymers with highly organized structures. The device is compatible with organic solvents. Reactants are loaded into pairs of reservoirs connected by a 15 cm long microchannel prefilled with solvents, thus allowing long‐term counter diffusion for self‐assembly of organometallic polymers. The process can be monitored, and the resulting crystalline polymers are harvested without damage. The device was used to synthesize three insoluble silver acetylides as single crystals of X‐ray diffraction quality. Importantly, for the first time, the single‐crystal structure of silver phenylacetylide was determined. The reported approach may have wide applications, such as crystallization of membrane proteins, synthesis and crystal growth of organic, inorganic, and polymeric coordination compounds, whose single crystals cannot be obtained using traditional methods.

Mechanistic study of silver-mediated furan formation by oxidative coupling.

Density functional calculations and experiments have been carried out to unravel the mechanism of a silver-mediated furan formation by oxidative coupling. Various possible reaction paths were considered and the most favorable channel has been identified on the basis of the calculated solvent-corrected Gibbs free-energy profiles. The mechanism represented by this route consists of a radical and a subsequent ionic route. The silver cation has a double role in the mechanism: it is the oxidant in the radical steps and the catalyst for the ionic steps, which is in accordance with the experimental observations. The two most important aspects of the optimal route are the formation of a silver-acetylide, reacting subsequently with the enolate radical, and the aromatic furan-ring formation in a single step at the latter, ionic segment of the reaction path. Our findings could explain several experimental observations, including the "key-promoter role" of silver, the preference for ionic cyclization, and the reduced reactivity of internal acetylides.

Chemical stability of olefin carrier based on silver cations and metallic silver nanoparticles against the formation of silver acetylide for facilitated transport membranes

Facilitated transport membranes containing silver cations and metallic Ag nanoparticles (NPs) as an olefin carrier have high olefin permeability and selectivity over propane. Silver ions are known to readily react with acetylene in aqueous conditions to produce silver acetylide, which can explosively decompose at temperatures over 160°C, and therefore its formation should be avoided. In this regard, we examined whether silver acetylide from olefin carriers such as free silver cations and surface-activated Ag NPs by 7,7,8,8-tetracyanoquinodimethane (TCNQ) is formed upon exposure to acetylene, which is present as a minor impurity in many petrochemical feeds. The results showed that silver acetylide was not formed from the activated Ag NPs under the current experimental conditions, while free silver cations of polymer electrolyte produced silver acetylide by reacting with acetylene. Therefore, it is concluded that the activated Ag NPs showed superior chemical stability, compared to free silver cations.

Distortion of ethyne on coordination to silver acetylide, C2H2⋅⋅⋅AgCCH, characterised by broadband rotational spectroscopy and ab initio calculations

The rotational spectra of six isotopologues of a complex of ethyne and silver acetylide, C2H2⋅⋅⋅AgCCH, are measured by both chirped-pulse and Fabry-Perot cavity versions of Fourier-transform microwave spectroscopy. The complex is generated through laser ablation of a silver target in the presence of a gas sample containing 1% C2H2, 1% SF6, and 98% Ar undergoing supersonic expansion. Rotational, A0, B0, C0, and centrifugal distortion ΔJ and ΔJK constants are determined for all isotopologues of C2H2⋅⋅⋅AgCCH studied. The geometry is planar, C2v and T-shaped in which the C2H2 sub-unit comprises the bar of the "T" and binds to the metal atom through its π electrons. In the r0 geometry, the distance of the Ag atom from the centre of the triple bond in C2H2 is 2.2104(10) Å. The r(HC≡CH) parameter representing the bond distance separating the two carbon atoms and the angle, ∠(CCH), each defined within the C2H2 sub-unit, are determined to be 1.2200(24) Å and 186.0(5)°, respectively. This distortion of the linear geometry of C2H2 involves the hydrogen atoms moving away from the silver atom within the complex. The results thus reveal that the geometry of C2H2 changes measurably on coordination to AgCCH. A value of 59(4) N m(-1) is determined for the intermolecular force constant, kσ, confirming that the complex is significantly more strongly bound than hydrogen and halogen-bonded analogues. Ab initio calculations of the re geometry at the CCSD(T)(F12(*))/ACVTZ level of theory are consistent with the experimental results. The spectra of the (107)Ag(13)C(13)CH and (109)Ag(13)C(13)CH isotopologues of free silver acetylide are also measured for the first time allowing the geometry of the AgCCH monomer to be examined in greater detail than previously.

Solvothermal Synthesis of Four Polyoxometalate-Based Coordination Polymers Including Diverse Ag(I)···π Interactions

Four 3D POM-based silver coordination polymers, namely, [Ag17(ptz)11(PW12O40)2]n (1), [Ag17(ptz)11(PMo12O40)2]n (2), [Ag12(ptz)6(CN)2(SiW12O40)]n (3), and [Ag19(ptz)8(H2ptz)(H3ptz)(AgP5W30O110)·7H2O]n (4), have been obtained by solvothermal reaction of AgNO3 and 5-phenyl-1H-tetrazole (Hptz) ligand in the presence of four types of polyoxometalates. Structural analysis shows that four types of Ag(I)···π interactions, m-η(1), m/p-η(2), o/m-η(2), and o/m/p-η(3), were observed in compounds 1-4, depending on the polyoxometalates used. The in situ generated CN(-) ion in compound 3 shows unprecedented mixed σ and π bonding modes, similar to the C2(2-) ion in well-studied silver acetylides. For 4, the Na(+) ion in the Preyssler heteropolyoxoanion, [NaP5W30O110](14-), was exchanged by Ag(I) under solvothermal conditions, generating a novel [AgP5W30O110](14-) anion. In addition, the photoluminescence behavior of 1-4 was also investigated.

C[sbnd]H and C[sbnd]C bond activation reactions in silver alkynyl cluster cations, RC[tbnd6]CAg2+

A range of silver alkynyl cations RCCAg2+ (R=H, Me, Et, Pr, Bu, tBu and Ph) can be “synthesized” in the gas phase via two approaches using electrospray ionization (ESI) multistage mass spectrometry experiments. The first involves injecting a solution of AgNO3 and the appropriate acid RCCCO2H in a MeOH/H2O solvent mixture into the ESI source, which yields the cluster cations (RCCAg)nAg+ (n=1–12) via decarboxylation. The second involves direct ESI of solutions of pre-synthesized silver acetylides, which yields a series of silver acetylide cluster cations of the type (RCCAg)nAg+ (n=4–18), which upon CID yield RCCAg2+. The low energy CID reactions of the silver alkynyl cations RCCAg2+ have been studied in a linear ion trap mass spectrometer. The rich fragmentation reactions observed included various combinations of CC and CH bond activation to yield the ionic products: (1) CH3CCAg2+ (R=Pr, Bu); (2) Ag2H+ (R=Et, Pr, Bu, tBu); and (3) HCCAg2+ (R=tBu). Other fragmentation channels observed include; AgC bond cleavage and loss of Ag+. CID of the deuterium labelled cation, CD3CH2CH2CCAg2+ (m/z 284), show that: H/D scrambling is not involved in either the loss of CD2CH2 or the formation of Ag2H+ (m/z 215). Formation of the latter ion involves the regioselective activation of the CH bond β to the triple bond, as revealed by the formation of Ag2D+ (m/z 216) in the CID spectrum of the deuterium labelled cation, CD3CD2CH2CCAg2+ (m/z 286).

Sp–sp3Coupling reactions of alkynylsilver cations, RCCAg2+(R = Me and Ph) with allyliodide

Alkynylsilver cations, RC≡CAg2(+) (where R = Me and Ph) have been prepared in the gas phase using multistage mass spectrometry experiments in a quadrupole ion trap mass spectrometer. Two methods were used: (i) electrospray ionisation (ESI) of a mixture of AgNO3 (in MeOH/H2O/acetic acid) and the alkyne carboxylic acid to yield the appropriate silver acetylide cations RC≡CAg2(+), via a facile decarboxylation of the RC≡CCO2Ag2(+) precursor; (ii) ESI of silver acetylides, RC≡CAg, which yields a cluster of the type, [(RC≡CAg)12Ag2Cl](+). Regardless of the method of preparation, these alkynylsilver cations, RC≡CAg2(+), undergo ion-molecule reactions with allyliodide to yield the ionic products Ag2I(+) and [(RC≡CCH2CH=CH2)Ag](+). The CID spectrum of [(PhC≡CCH2CH=CH2)Ag](+) was compared to that of an authentic sample of the silver adduct of 5-phenyl-1-penten-4-yne. Both ions fragment to yield Ag(+) and the radical cation, PhC≡CCH2CH=CH2(+)˙, confirming that C-C bond coupling has taken place in the gas phase. DFT calculations were carried out on these C-C bond coupling reactions for the system R = Me. The reaction is highly exothermic and involves the initial coordination of the allyliodide to both silver atoms, with the iodine coordinating to one atom and the alkene moiety coordinating to the other. The overall mechanism of C-C bond coupling involves oxidative addition of the allyliodide followed by reductive elimination of RC≡CCH2CH=CH2, to ultimately yield two sets of reaction products: (i) Ag2I(+) and RC≡CCH2CH=CH2; and (ii) [(RC≡CCH2CH=CH2)Ag](+) and AgI.