Cyclorheniated Azabutadienes and Their Reactions with Unsaturated Molecules

Abstract

This thesis reports the studies on the reaction of 1-azabutadienes with PhCH2Re(CO)5 to prepare the cyclometallated azabutadiene tetracarbonyl compounds.

Three 1-azabutadienes with different reactivity on the N and C-1 carbons were prepared and their reactions with PhCH2Re(CO)5 were investigated.

All the reactions gave a mixture of the cyclorheniated azabutadienes and the isomers of the substituted derivatives formed by substitution by a second azabutadiene.

The substituted derivatives as the mixture were always the main products of the reactions and were obtained in good-to-excellent yield even under modified conditions intended to optimise the yield of the cyclorheniated azabutadienes. The yield could not be improved beyond 30 %. Isomerisation of the azabutadiene about the N=C bond provided very rare cis-azabutadiene metal complexes. NMR studies on the mixture of the two isomers and suggested that the product ratio depended on the molar ratio of PhCH2Re(CO)5 in the reaction mixtures.

The reactions gave the Re analogues of the products obtained in the corresponding Mn reactions.

All the compounds were characterised spectroscopically as well as by microanalysis and examples of all three types were structurally determined by X-ray crystallography.

The reactions of the substituted derivative as the mixture of the two isomers with unsaturated molecules including phenyl acetylene, p-methoxyphenyl isocyanide, and phenyl isocyanate and methyl acrylate were investigated.