Protonation of tricarbonyl(cyclo-octatetraene)-ruthenium gives a tricarbonyl(bicyclo[5,1,0]octadienium)-ruthenium cation, which isomerises to [h5-1,2,5,6,7-C8H9Ru(CO)3]+; similar reaction occurs with α-C8H8Os(CO)3; the reaction of [h5-1,2,5,6,7-C8H9Ru(CO)3]+ with CN– and CH2NO2– is described.
