Silver complexes carbon-donors

Crown ether 4 has been shown to be a source of unusual dinuclear silver(l) complexes <2002ICA(332)18>. In the crystal, the silver ions interact with the crown ether ligand at both the hard donor ethereal oxygens and soft benzene ring carbon atoms via intermolecular cation-Tt-interaction in -fashion, as depicted in Figure 6. The dimeric structure is further stabilized by the occurrence of intermolecular Tt-Tt-intcractions between facing benzo groups. 

Until recently, isolable CO complexes of silver were unknown. However, if the counteranion possesses only very weak basicity, fairly stable CO adducts are obtained. Carbon monoxide acts in these compounds as a donor ligand only. Back-bonding is virtually absent, and the C—O stretching frequencies are substantially higher than that of free CO (2143 cm"1). The compounds [Ag(CO)]+X" (vqo = 2204 cm"1) and [OC—Ag—CO]+X (vco = 2198 cm-1) [X = B(OTeF5)4] were characterized by X-ray diffraction.21 The [Ag(CO)3]+ ion is formed under CO pressure. 

Silver(i).-Group VII Donor Ligands. AW-Dimethylthioformamide complexes AgCl,-2DMTF, AgBr,2DMTF, and AgI,DMTF have been characterized in solution and in the solid state, and the dissociation constant for reaction (26) was determined from conductivity measurements. Complex solubilities of AgX (X = Cl, Br, or I) have been determined in benzonitrile and trichloroacetonitrile mixtures with propylene-carbonate.The results were compared with previous work in acetonitrile and propionitrile. 

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