THE STRUCTURE OF C(5)H(5)RFE(-PHASE AND THE GENERATION OF THEIR NEUTRAL COUNTERPARTS BY NEUTRALIZATION-REIONIZATION MASS-SPECTROMETRY() (R=F, CL, BR, I, O, OH, OCH3, C6H5, H) IONS IN THE GAS)

The structure of C(5)H(5)FeR(+.) ions was studied by tandem mass spect rometry that included the neutralization-reionization (NR) method. Hal ogen-containing species (R = F, Cl, Br, I) showed fragmentation that w as consistent with a structure that has the cyclopentadienyl ring and R as separate ligands at the metal atom (structure A). This structure also was identified for C5H5FeO+ and CpFeOH(+.) ions, but these specie s also easily isomerized to metal-cyclepentadiene structure, RC(5)H(5) Fe(+.) (B), followed by hydrogen rearrangement(s) and CO loss. B was t he dominant structure of C5H5FeH+. and C5H5FeC6H5+. ions. All ions tha t have structure A showed recovery signals in their NR mass spectra th at indicated that their stable neutral counterparts were generated. Th e NR mass spectra also provided complementary information about the st ructure of ions before neutralization and after reionization.