Further Astrochemical Insights From Bond Strengths of Small Molecules Containing Atoms From the First Three Rows of the Periodic Table

Edmund S Doerksen,Ryan C Fortenberry

doi:10.3389/fspas.2021.723530

Edmund S Doerksen, Ryan C Fortenberry

Open Access

https://doi.org/10.3389/fspas.2021.723530

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Abstract

The atoms contributing to the strongest “single bonds” on the periodic table do not continue to produce the strongest “double bonds” or “triple bonds.” In fact, the opposite appears to be the case. This quantum chemical examination of nominal X = Y and X ≡ Y bonds in model molecules of atoms from the first three rows of the periodic table shows that the strongest “double bond” is in formaldehyde once the astrophysically-depleted Be and B atoms are removed from consideration. The strongest “triple bond” is a close match between acetylene and N2. However, these results indicate that astrophysical regions containing a high abundance of hydride species will likely be areas where inorganic oxide formation is favored. Those where H2 molecules have already been dissociated will favor organic/volatile astrochemistry.

Highlights

Recent work has shown that the strongest “single bonds” in neutral molecules for atoms on the first three rows of the periodic table are not between the atoms most commonly used in chemistry (Doerksen and Fortenberry, 2020)
The m and n values are the number of hydrogen atoms necessary to fill the valency where a single bond is created between the heavy atoms
The results of the previous (Doerksen and Fortenberry, 2020) and present work imply that hydrogen-rich environments may very well favor gas phase formation of small molecules containing inorganic and refractory atoms as such molecules contain the strongest heavy atom bonds in molecules with highest molar percentage of hydrogen

Summary

INTRODUCTION

Recent work has shown that the strongest “single bonds” in neutral molecules for atoms on the first three rows of the periodic table are not between the atoms most commonly used in chemistry (Doerksen and Fortenberry, 2020). This previous work (Doerksen and Fortenberry, 2020) did not examine any molecules containing period 4 atoms or higher largely due to a combination of factors including the statistical increase in the sample set, the decrease in atomic abundance (save for Fe, ), and the complexities of electronic structure computations on molecules involving the mid-row transition metal atoms, most notably iron (DeYonker, 2015) In this previous study, the X−Y bond strengths are computed from model HmX − YHn molecules (Doerksen and Fortenberry, 2020). If the heavy atom bond strength in HAlO is higher than in AlH2OH, such a result would be one piece of supporting evidence for the hypothesis that hydrogen removal begins earlier in the nanocrystal aggregation stage. The stabilities of these small molecules may offer clues as to whether or not such species may be present in astrophysical regions (Fortenberry, 2020; Fortenberry and DeYonker, 2021) regardless of their roles in any subsequent chemistry or materials formation

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CONCLUSION