Intracluster Ion Molecule Reactions Following the Generation of Mg+ Within Polar Clusters

Edreese H Alsharaeh

doi:10.3390/ijms12129095

Abstract

In this work we investigated the intracluster ion molecule reactions following the generation of Mg+ within the polar clusters (water, methanol, ether and acetonitrile), using time of flight mass spectrometry. In the case of Mg+/water and Mg+/methanol, dehydrogenation reactions are observed after the addition of five molecules. However, no dehydrogenation reactions are observed in the case of Mg+/ether or Mg+/acetonitrile clusters. This confirms the role of the H atom in (O–H) in the dehydrogenation reaction, and rules out any contribution from the H atom in the CH3 group. In addition, the magic numbers in the time of flight (TOF) mass spectra of the Mg+Xn clusters (X = H2O, CH3OH, CH3OCH3 and CH3CN) have been investigated. Finally, the role of ground electronic magnesium ion Mg+(2S1/2), and excited electronic magnesium ion Mg+(2P1/2) in the dehydrogenation reaction were investigated using Ion Mobility Mass spectrometry. The results offer direct evidence confirming the absence of the electronically excited, Mg+(2P1/2).

Highlights

Reactions in solutions are highly dependent upon the medium used, and among them ion molecule reactions represent the best systems to study solvation effects at a microscopic level [1]
The results show that the energy required to lose an H atom decreases with the number of water molecules attached, because the magnesium ion changes its oxidation state and this results in stronger interactions with the water ligands
CH3CN were investigated using pulsed supersonic beam expansion coupled with laser vaporization and mass spectrometry techniques

Summary

Introduction

Reactions in solutions are highly dependent upon the medium used, and among them ion molecule reactions represent the best systems to study solvation effects at a microscopic level [1]. The results show that the energy required to lose an H atom decreases with the number of water molecules attached, because the magnesium ion changes its oxidation state and this results in stronger interactions with the water ligands These experimental results differ from those of Saneketa et al [3] who observed the first product switching at n = 5, and attributed this result to the low temperature of the cluster beam source. The solvation of Mg+ with polar solvents such as H2O, CH3OH, CH3OCH3, and CH3CN were investigated using pulsed supersonic beam expansion coupled with laser vaporization and mass spectrometry techniques This allows further investigation of the role of polar solvents, role of ground electronic magnesium ion Mg+(2S1/2), and excited electronic magnesium ion Mg+(2P1/2) in the dehydrogenation reaction. It would be interesting to see whether H– elimination or CH3– elimination is the dominant process

Experimental Results

Discussion

Experimental Section

Conclusions