Synthesis and some reactions of π-cyclo-octatrienyl-π-cyclo-octatetraenecobalt
Abstract
Reduction of cobaltous chloride with sodium borohydride in the presence of cyclo-octatetraene gives in low yield π-h5-cyclo-octatrienyl-π-1,2,3,4-tetrahapto-cyclo-octatetrenecobalt (I), the first fluxional cyclo-octatetraene-cobalt complex. Carbon monoxide displaces cyclo-octatetraene from (I) to give tricarbonyl-π-h3-cyclo-octatrienylcobalt (II). Cyclopentadiene and indene react with (I) to form respectively, cyclo-octa-1,3,6-trienyl-π-cyclopentadienylcobalt (III) and cyclo-octa-1,3,6-trienyl-π-indenylcobalt (V). At higher temperatures indene reacts with (I) to form 1,2,5,6-tetrahapto-cyclo-octatetraene-π-indenylcobalt. Variable temperature 1H n.m.r. measurements suggest that (V) exists in two rotational isomeric forms.