Generation of “unstable” complexes of carbon dioxide with Pb2+ and Sn2+ under electron ionization conditions

A number of metal acetates are analysed by electron ionization mass spectrometry (EI-MS). The acetates of Sn(II) and Pb(II/IV) yield peaks of doubly charged ions, namely the complexes of Sn2+ and Pb2+ with CO2 molecule(s). The second ionization energies of lead and tin are higher than the first ionization energy of CO2, thus, the doubly charged complexes observed are asymptotically unstable. Electron ionization is regarded as the so-called hard ionization method, therefore it was unexpected that unstable ions would form under such conditions.

Graphical abstractThe acetates of Sn(II) and Pb(II/IV) yield, on EI mass spectra, peaks of the asymptotically unstable complexes of Sn2+ and Pb2+ with CO2 molecule(s). [Sn + (CO2)2]2+m/z 104, [Sn + CO2]2+m/z 82.Figure optionsDownload full-size imageDownload high-quality image (52 K)Download as PowerPoint slide