THE APPLICATION OF ELECTROSPRAY MASS-SPECTROMETRY TO IONIC INORGANIC AND ORGANOMETALLIC SYSTEMS

Electrospray mass spectra have been observed for a number of ionic inorganic and organometallic compounds in dichloromethane/methanol (1:10) solutions. Intact principal ions were observed directly for [PPh3Bz]+, NBu4PF6 (positive and negative), [Fe(C5H5)2]+ and trans-[Cr(CO)2(dpe)2]+ (dpe = Ph2PCH2CH2PPh2). The non-ionic compound Re(CO)2Br(eta1-dpm)(eta2-dpm) (dpm = Ph2PCH2PPh2) was reacted with MeI to convert the pendant phosphorus to a phosphonium salt to give [Re(CO)2Br(eta1-dpmMe)(eta2-dpm)]I whose principal ion was observed. The heteropolymolybdate (NEt4)4[S2Mo18O62] in acetonitrile solution gave the intact [S2Mo18O62]4- ion. These systems show that electrospray mass spectrometry has great promise for investigating ionic compounds, particularly those that are not amenable to mass spectrometric studies via other ionization techniques.