CF-252 PLASMA DESORPTION MASS-SPECTROMETRY AS A TOOL FOR STUDIES OF METALLOCENES

Plasma desorption mass spectra of a zirconocene and two ferrocenyl phenyl plumbanes have been obtained in both positive- and negative-ion modes with a linear time-of-flight instrument, For molecular weight determination of the ferrocenes the positive-ion mass spectra exhibit radical molecular ions with high abundance. The zirconocene compound shows no molecular ion at all, but shows a [M - Cl]+ ion. The positive-ion mass spectra in particular provide detailed structural information. In the case of the ferrocenes the negative-ion mass spectra show fragment ions which give information complementary to the positive mode. Samples have been prepared by the electrospray technique, by spin-deposition on nitrocellulose as support and on 3-(3-pyridyl)acrylic acid as matrix. In addition, the potential of a reflecting time-of-flight instrument with a higher mass resolution for the molecular ion and lead isotope region of the ferrocenes has been demonstrated. The isotopic pattern of the M.+ ion and Pb+ ion obtained in the reflector mode for an electrosprayed and nitrocellulose spin-deposited sample was compared with the theoretically calculated pattern. An excellent correlation was found for the nitrocellulose deposition technique.