Silver Acetylide Complexes

Catalytic forms of copper, mercury and silver acetylides, supported on alumina, carbon or silica and used for polymerisation of alkanes, are relatively stable [3], In contact with acetylene, silver and mercury salts will also give explosive acetylides, the mercury derivatives being complex [4], Many of the metal acetylides react violently with oxidants. Impact sensitivities of the dry copper derivatives of acetylene, buten-3-yne and l,3-hexadien-5-yne were determined as 2.4, 2.4 and 4.0 kg m, respectively. The copper derivative of a polyacetylene mixture generated by low-temperature polymerisation of acetylene detonated under 1.2 kg m impact. Sensitivities were much lower for the moist compounds [5], Explosive copper and silver derivatives give non-explosive complexes with trimethyl-, tributyl- or triphenyl-phosphine [6], Formation of silver acetylide on silver-containing solders needs higher acetylene and ammonia concentrations than for formation of copper acetylide. Acetylides are always formed on brass and copper or on silver-containing solders in an atmosphere of acetylene derived from calcium carbide (and which contains traces of phosphine). Silver acetylide is a more efficient explosion initiator than copper acetylide [7],... 

On the basis of the above-mentioned calculations it seems that coordination chemistry is a viable alternative to stabilize this heterocumulene. However, the experimental access to metal complexes containing the tricarbon monoxide ligand remains a challenge. Thus, to date, the coordination chemistry of C3O is confined to [Cr(=C=C=C=0)(C0)s] (89), obtained by treatment of [n-Bu4N] [CrI(CO)5] with the silver acetylide derived of sodium propiolate in the presence of Ag" (Scheme 28) [105]. Reaction of the presumed Tt-alkyne intermediate complex 88 with thiophosgene generates the heterocumulene 89. Neither structural nor reactivity studies were undertaken with this complex. 

Disilver Aeetylide + Silver Nitrate (Complex) (Silver Acetylide-Silver Nitrate), AgaCa AgNOj or AgjCjNOj, mw 409.67, N3.42%. Wh pdr,d 5.38(Ref 5) mp-deton ca 212 Ref 6). 

Disilver Acetylide 4 Six Silver Nitrates (Complex), AgjCj+6AgNOs or Cj Ag N60lft, crysts, mp-when heated to 308-327°it melts and then suddenly decomp with evoln of red fumes. Can be prepd by passing CaHa through a 30 soln of AgNOj in HaO or N/l HNOr It is not expl... 

Disilver Acetylide 4 Silver Iodide (Complex), AgjCa. Agl or [ AgjCj] I gm vety expl ppt. Can be prepd from CaHa and an ammoniacal soln of freshly prepd Agl, taken in excess Refs l)Beil 1,241 2)M.Berthelot M-... 

K bromide solns v si sol in w. It occurs in nature as the mineral born silver and is formed when a soln of a sol chloride is added to a soln of a Ag salt. Silver chloride in contact with metallic Na or K is exploded by percussion (Ref 3). Its ammoniacal soln absorbs acetylene, forming Silver Acetylide Chloride complexes which are expl (See Vol 1, p A80 l. Silver chloride is used in medicine as an antiseptic nerve sedative, in the manuf of pure Ag Ag salts, and in photography photometry(Refs... 

Mercuric Acetylide + Three Silver Nitrates (Complex), HgCj + 3AgNO. Wh crysts, decomp on heating without expln. Can be prepd by treating Ag2Cj + 6AgNOs with sufficient Hg(NOs)2 in HNOs soln to ppt the HgQ + 3AgNOs... 

Disilver Acetylide + Di silver Sulfate Complex, (Ag2C2). Ag2S04 or (AgsC2)AgS04, wh ppt, deton weakly in vacuo. Can be prepd by treating C2H2 with an excess of silver sulfate in soln... 

Two Disilver Acetylides + Silver Chloride (Complex), (Ag2C2)2. AgCl or Ag2C2 +... 

Pale and coworkers have demonstrated that silver acetylides may be synthesized with a variety of silver salts in the presence of base in a number of solvents. By treating 1 -hexyne in either deuterated benzene or DMF with silver triflate, the group was able to observe the formation of the Jt-alkyne-silver complex and subsequently the silver acetylide through the use of H, C, and Ag NMR. The incipient Jt-alkyne-silver complex is rapidly deprotonated on addition of diisopropylethylamine, to give the silver acetylide as a white precipitate (Scheme 1.33).89... 

Although catalytic amounts of Ag20 have been found to promote the palladium-catalyzed coupling of aryl boronic acids and terminal alkynes, the authors in this case do not attribute the desired reactivity to the formation, and subsequent transmetalla-tion, of a silver acetylide. Rather, it is proposed that the Ag20 activates the alkynylpalladium complex to allow transmetallation from the boronic acid, and that any competing formation of the silver acetylide results in a homocoupling of the alkynes (Scheme 1.55).123... 

By analogy to aurophilicity, argentophilicity has been demonstrated to exist in silver cluster complexes. In the crystal structures of a variety of silver double and multiple salts containing a fully encapsulated acetylide dianion C (IUPAC name acetylenediide) in different polyhedral silver cages (see Fig. 14.3.11), there exist many Ag- -Ag contacts shorter than twice the van der Waals radius of silver (2 x 170 = 340 pm). Further details are given in Chapter 20. 

Vinyliodonium ions, 35 and 36, are hypervalent iodine species in which one or two alkenyl ligands are bound to a positively charged iodine(III) atom. Although they are reactive with nucleophilic reagents, they are less labile than alkynyliodonium ions, and stable halide salts of vinyliodonium ions can be prepared. The first vinyliodonium compounds [i.e. (a, / -dichlorovinyl)iodonium salts] were synthesized by the treatment of silver acetylide-silver chloride complexes with (dichloroiodo)arenes or l-(dichloroiodo)-2-chloroethene in the presence of water (equation 152). The early work was summarized by Willgerodt in 1914115. This is, of course, a limited and rather impractical synthetic method, and some time elapsed before the chemistry of vinyliodonium salts was developed. Contemporary synthetic approaches to vinyliodonium compounds include the treatment of (1) vinylsilanes and vinylstannanes with 23-iodanes, (2) terminal alkynes with x3-iodanes, (3) alkynyliodonium salts with nucleophilic reagents and (4) alkynyliodonium salts with dienes. 

Silver(I)-catalyzed cyclizations of substituted allenes to heterocydic ring systems induding 2,5-dihydropyrroles have been described previously [4,10]. Moreover, sil-ver(I) salts are known to form stable rr-complexes with terminal acetylenes [11]. On the other hand, on treatment with silver nitrate silylacetylenes were reported to afford silver acetylides [12]. Based on these considerations and additional experimental evidence [5,13], the following mechanism has been proposed forthe sUver(I)-mediated oxidative cydization of homopropargylamines to pyrroles ]5] (Scheme 15.3). 

Note According to R.Vestin E.Ralf, Acta ChemScandinavica 3,106(1949) Beil 1, i910l this complex does not exist Monosilver Acetylide + Silver Nitrate (Complex), AgHCj. AgNO, or AgHCjNOj Solid, expl violently ca 230° Can be prepd from and an aq soln of silver nitrate, as described in Ref 2... 

Disilver Acetylide + Silver Nitrate (Complex) (Silver Acetylide-Silver Nitrate), AgjC,... 

Silver alkyls and aryls, together with silver(I) complexes of cyclic polyenes and aUcynyl ligands, are generally classified under organometallic compounds. Stable silver(l) carbonyl complexes that have been characterized by X-ray analysis include [Ag(CO) B(OTeF5)4 ], [Ag(CO)2 B(OTeF5)4 ], and [Ag(CO) HB[3,5-(CF3)2pz]3 ]. Silver acetylide (AgzCz) complexes are described in Section 3.6. 

Several silver(I) complexes with crown ethers and calixarenes have been synthesized. In the design of discrete molecules and infinite chains in silver acetylide chemistry, crown ethers function as blocking groups or protective cordons around a polyhedral C2 Ag cage so that the isolation of lower-dimensional supramolecular entities can be achieved. " ... 

Complex anionic silver acetylides, K[Ag(CCR)2] (R = H, Me, Ph), are known and are prepared from the appropriate alkynylsilver and the potassium acetylide in a polar solvent. They are colorless crystalline solids that are sensitive to light and that decompose in solution. They apparently are not explosive. 

---