Cyclooctadiene complexes with silver

Complexes with alkenes and arenes are formed when the hydrocarbons are shaken with aqueous solutions of silver(I) salts. Di- or polyalkenes often give crystalline compounds with Ag+ bound to one to three double bonds. The formation of alkene complexes of varying stability may be used for the purification of alkenes, or for the separation of isomeric mixtures (e.g., 1,3-, 1,4-, and 1,5-cyclooctadienes), or of the optical isomers of a- and /3-pinene. There is very little back-bonding contribution in the formation of Ag1 rr-complexes. For example, the planar complex (hfa)Ag(Ph-C= C-Ph) contains an almost linear acetylene ligand with a C=C... 

The oligomerization and cooligomerization of conjugated dienes are representative reactions that proceed via transition-metal Jt-allyl intermediates. When (CsMesjRuCljt/ -butadiene) in dichloromethane was treated with an acetone solution of an equimolar amount of silver trifluoromethanesulfonate (AgOTf) in the presence of excess butadiene at ambient temperature, after which the mixture was allowed to react with carbon monoxide (1 atm), a cationic 1,5-cyclooctadiene carbonyl complex, [(C5Me5)Ru(CO)( -l,5-C8Hi2)]OTf, was isolated in 95% yield (Eq. 

Electrolysis at copper electrodes of cupric perchlorate with 1,5-cyclooctadiene in methanol yields well-defined crystals of an air-stable cuprous complex (CgHi2)2CuC104 (390). The C=C stretching band at 1660 cm in the diene is replaced by two bands at 1638 and 1595 cm" in the complex, suggesting nonequivalent coordination of the double bonds. As with the silver-olefin complexes (492) there is a dependence... 

The reaction of (93b) with Pt(COD)Cl2 gave (96) and when the reaction was carried out in the presence of silver tetrafluoroborate, the crystalline salt (97) was formed. An X-ray crystallographic structure determination of (97) showed a distorted tbp around phosphorus with the platinum fragment in an equatorial position and a near square-planar coordination geometry around the Pt atom. On heating to 60°C, (97) lost cyclooctadiene to form (98). Variable temperature P NMR studies were reported for (96) and (97). This work, using ligands (92) and (93a), was extended to complexes of Pt and Rh with similar results. ... 

For olefin Ti-complexes, copper(II) halides as fine powders react with butadiene, norbornadiene, cyclooctadiene or dicyclopentadiene to give the corresponding olefin complex (2-4). Some olefins readily form silver nitrate complexes (2-5) in an aqueous or alcoholic solution. 

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