Exploring the nature of silicon-noble gas bonds in H3SiNgNSi and HSiNgNSi compounds (Ng = Xe, Rn).

Sudip Pan,Ranajit Saha,Pratim Chattaraj

doi:10.3390/ijms16036402

Abstract

Ab initio and density functional theory-based computations are performed to investigate the structure and stability of H3SiNgNSi and HSiNgNSi compounds (Ng = Xe, Rn). They are thermochemically unstable with respect to the dissociation channel producing Ng and H3SiNSi or HSiNSi. However, they are kinetically stable with respect to this dissociation channel having activation free energy barriers of 19.3 and 23.3 kcal/mol for H3SiXeNSi and H3SiRnNSi, respectively, and 9.2 and 12.8 kcal/mol for HSiXeNSi and HSiRnNSi, respectively. The rest of the possible dissociation channels are endergonic in nature at room temperature for Rn analogues. However, one three-body dissociation channel for H3SiXeNSi and one two-body and one three-body dissociation channels for HSiXeNSi are slightly exergonic in nature at room temperature. They become endergonic at slightly lower temperature. The nature of bonding between Ng and Si/N is analyzed by natural bond order, electron density and energy decomposition analyses. Natural population analysis indicates that they could be best represented as (H3SiNg)+(NSi)− and (HSiNg)+(NSi)−. Energy decomposition analysis further reveals that the contribution from the orbital term (ΔEorb) is dominant (ca. 67%–75%) towards the total attraction energy associated with the Si-Ng bond, whereas the electrostatic term (ΔEelstat) contributes the maximum (ca. 66%–68%) for the same in the Ng–N bond, implying the covalent nature of the former bond and the ionic nature of the latter.

Highlights

Having a late break-through in 1962 with the discovery of Xe+[PtF6]−, chemistry related to the noble gas (Ng) compounds has been developing very rapidly, especially during the last two decades
The transition states (TSs) corresponding to the dissociations of H3SiNgNSi and HSiNgNSi into Ng and H3SiNSi or HSiNSi have Cs (TS-1 in Figure 1) and C1 (TS-2 in Figure 1) symmetry, respectively, in which the NSi fragment remains attached with H3SiNg or HSiNg fragments in a tilted fashion
The geometrical parameters of H3SiNgNSi and HSiNgNSi compounds obtained at the ωB97X-D/def2-QZVPPD and CCSD(T)/def2-TZVP levels are provided in Table S1

Summary

Introduction

Having a late break-through in 1962 with the discovery of Xe+[PtF6]−, chemistry related to the noble gas (Ng) compounds has been developing very rapidly, especially during the last two decades. We studied the Ng binding ability of the SiH3+ cluster, as well as the effect of H substitution of SiH3+ by halide groups (–X) on its ability in binding Ng [68]. In this manuscript, we have reported two new viable compounds, H3SiNgNSi and HSiNgNSi (Ng = Xe, Rn), with Si-Ng covalent bonds. We have assessed in silico the structure, stability and the nature of bonding in H3SiNgNSi and HSiNgNSi compounds They are found to be metastable systems. For the first time, we reported here the neutral Rn-containing compounds, H3SiRnNSi and HSiRnNSi, with the Si–Rn covalent bond

Structure and Stability

Nature of Bonding

Experimental Section

Conclusions