Cyclooctatetraene complexes silver

It is also not clear why the diolefin 1,5-cyclooctadiene forms a weaker bond to silver than cyclooctene. The effects of strain differences within the olefins and/or within the complexes is not apparent30, but in any case suggests, as noted by the original authors, a negligible interaction between the metal and the second double bond. However, the cyclooctatetraene complex is asserted to be polymeric in solution and so currently precludes obtaining useful information derived from these complexation studies of this species. 

Among the compounds that form complexes with silver and other metals are benzene (represented as in 9) and cyclooctatetraene. When the metal involved has a coordination number >1, more than one donor molecule participates. In many cases, this extra electron density comes from CO groups, which in these eomplexes are called carbonyl groups. Thus, benzene-chromium tricarbonyl (10) is a stable compound. Three arrows are shown, since all three aromatic bonding orbitals contribute some electron density to the metal. Metallocenes (p. 53) may be considered a special case of this type of complex, although the bonding in metallocenes is much stronger. 

Cyclooctatetraene (continued) with iron, 12 267-273 with nickel, 12 307, 308 with palladium, 12 315 with platinum, 12 319 with rhodium, 12 304 with ruthenium, 12 280 with silver, 12 340, 342, 343, 346 complexes of, 4 81 iron complexes of, 4 89 Cyclooctatriene complexes... 

Metal, TT complexes of cyclooctatetraene were first described by Reppe ei al. (211) in 1948. Silver and copper complexes were obtained during the synthesis of this hydrocarbon from acetylene. These complexes of cyclooctatetraene have since been investigated in considerable detail by several groups of investigators (50, 114, l j l )- An x-ray analysis of the complex [(CgHg)Ag]+N03 (XXIV) indicates that the silver ion is coordinated to two nonadjacent bonds of cyclooctatetraene but is situated at differences from each. [(CgHg)Ag]+ units are, furthermore, joined together by weak bonds. 

In the early 1980 s we started our structural studies on the series of benzannelated cyclooctatetraenes 18—21 and 7 and their n-complexes with silver(I) and copper (I) salts It turned out that our X-ray analysis of 19 and 7 were preceded by a... 

The best known of these complexes was cyclobutadiene silver nitrate prepared by Nenitzescu et al. (5). It was assigned structure (LXXXIX) on the basis of its method of preparation and some incorrect proton NMR data (4). A careful repetition of this work (3), however, show ed the complex to be the di(silver nitrate) complex of ryn-tricyclooctadiene (XC). In solution this complex isomerized to a cyclooctatetraene-silver nitrate complex which gave the originally observed (4) single proton resonance. 

A mixture of cycloocta-l,3,5-triene and cycloocta-l,3,6-triene formed by partial reduction of cyclooctatetraene is the usual starting point for the study of cyclooctatriene complexes, and obviously complexes may be derived from both isomers. Also, the 1,3,5-isomer is in thermal equilibrium with its valence tautomer, bicyclo[4.2.0]octa-2,4-diene (XXVII), at 100° C (30), from which complexes may also be formed. Although silver nitrate... 

A very similar study has been performed on the complex formed from silver nitrate and cyclooctatetraene 12,13). This polymeric complex is obtained by reaction of aqueous silver nitrate with cyclooctatetraene dissolved in petroleum ether. Like the benzene-silver perchlorate described above, this complex decomposes readily and hence was examined in an atmosphere of the ligand. Complete bond distance and angle data are available for its structure as shown in Table V.l 13). The molecular structure of the 1 1 silver nitrate-cyclo-octatetraene dimer has been determined by X-ray crystallographic analysis 15). 

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