STRUCTURE AND MECHANISMS OF FORMATION OF C6H6FE+ IONS PRODUCED BY ELECTRON-IMPACT ON ETA-5-C5H5FE(CO)2CH3

Collisional activation (CA) mass spectrometry has been employed to show that C6H6Fe+ ions formed upon electron impact of dicarbonyl-(eta-5-2,4-cyclopentadienyl)-methyliron consist of a 1:1 mixture of fulvene-iron and benzene-iron structures. Analysis of daughter-ion spectra of the deuterium-labelled analogue shows that there exist two independent fragmentation routes leading to the different ion structures. These routes differ in the sequence in which the CO ligands and H-2 are lost from the molecular ion.