Electron impact and chemical ionisation mass spectrometry in the characterisation of organometallic silicon, germanium, tin and lead compounds

Paraffin-Inert Atmospheric Solid Analysis Probe: A Fast and Easy Approach To Characterize Extremely Air-Sensitive Organometallic Complexes by Mass Spectrometry

Rational characterization of most organometallic compounds is hampered by their high reactivity, in particular, toward oxygen and water. Mass spectrometry experiments require physical introduction of the sample in the ionization source. So, the main challenge is to transfer air-sensitive organometallic compounds from inert atmosphere to the ionization source. In this aim, we have developed an easy technique that allows the analysis of air-sensitive compounds using the atmospheric solid analysis probe (ASAP). This method consists of a glass capillary filled with the sample (solid or liquid) and sealed by a paraffin plug to maintain the inert sample until the ionization process. It is illustrated through the structural characterization of a new highly air-sensitive dinuclear zirconium complex supported by an original switchable stilbene platform.

Structural analysis of organometallic compounds with soft ionization mass spectrometry

The analysis of organometallic compounds with mass spectrometry has some special features in comparison with organic and bioorganic compounds. The first step is the choice of a suitable ionization technique, where the electrospray ionization is certainly the best possibility for most classes of organometallic compounds and metal complexes. Some ionization mechanisms of organometallic compounds are comparable to organic molecules, such as protonation/deprotonation, and adduct formation with sodium or potassium ions; however, in many cases, different mechanisms and their combinations complicate the spectra interpretation. Organometallics frequently undergo various types of adduct and polymerization reactions that result in significantly higher masses observed in the spectra in comparison to molecular weights of studied compounds. Metal elements typically have more natural isotopes than common organic elements, which cause characteristic wide distributions of isotopic peaks; for example, tin has ten natural isotopes. The isotopic pattern can be used for the identification of the type and number of metal elements in particular ions. The ionization and fragmentation behavior also depend on the type of metal atom; therefore, our discussion of mass spectra interpretation is divided according to the different type of organometallic compounds. Among various types of mass spectrometers available on the market, trap-based analyzers (linear or spherical ion-traps, Orbitrap) are suitable to study complex fragmentation pathways of organometallic ions and their adducts, whereas high-resolution and high-mass accuracy analyzers (time-of-flight-based analyzers, or Fourier transform-based analyzers-Orbitrap or ion cyclotron resonance mass spectrometers) provide accurate masses applicable for the determination of the elemental composition of individual ions.