CAl4Mg0/−: Global Minima with a Planar Tetracoordinate Carbon Atom

Nisha Job,Maya Khatun,Krishnan Thirumoorthy,Anakuthil Anoop,Vijayanand Chandrasekaran,Venkatesan S Thimmakondu,Sasanka Sankhar Reddy Ch

doi:10.3390/atoms9020024

Abstract

Isomers of CAl4Mg and CAl4Mg− have been theoretically characterized for the first time. The most stable isomer for both the neutral and anion contain a planar tetracoordinate carbon (ptC) atom. Unlike the isovalent CAl4Be case, which contains a planar pentacoordinate carbon atom as the global minimum geometry, replacing beryllium with magnesium makes the ptC isomer the global minimum due to increased ionic radii of magnesium. However, it is relatively easier to conduct experimental studies for CAl4Mg0/− as beryllium is toxic. While the neutral molecule containing the ptC atom follows the 18 valence electron rule, the anion breaks the rule with 19 valence electrons. The electron affinity of CAl4Mg is in the range of 1.96–2.05 eV. Both the global minima exhibit π/σ double aromaticity. Ab initio molecular dynamics simulations were carried out for both the global minima at 298 K for 10 ps to confirm their kinetic stability.

Highlights

IntroductionThe concept of planar tetracoordinate carbon (ptC) or carbon group elements enthrals both experimentalists [1,2,3,4,5,6,7,8,9,10] and theoreticians [11,12,13,14,15,16,17,18,19] as it is a fundamental deviation from the conventional ideas of tetrahedral tetracoordinate carbon [20,21]
For CAl4Mg and CAl4Mg−, we identified 37 and 33 stationary points, respectively
Molecules with a planar tetracoordinate carbon (ptC) atom have been theoretically characterized for the first time in both CAl4Mg (1n) and CAl4Mg− (1a)

Summary

Introduction

The concept of planar tetracoordinate carbon (ptC) or carbon group elements enthrals both experimentalists [1,2,3,4,5,6,7,8,9,10] and theoreticians [11,12,13,14,15,16,17,18,19] as it is a fundamental deviation from the conventional ideas of tetrahedral tetracoordinate carbon [20,21]. The idea of ptC has been extended to planar hypercoordinate carbon (phC; penta [33,34,35] and hexa [36,37,38,39,40] coordination) as well as to other elements such as B [41,42] or N [43] considering their potential applications in material science [44,45]

Objectives

Results

Conclusion