Exploring the Structure and Bonding of Group 13 Homogeneous and Heterogeneous Hydrides with the X₂H₄ Stoichiometry: A Theoretical Investigation

Abstract

We investigated the structure evolution of the Group 13 hydrides on the example of X2H4 (X = B, Al, Ga, In, Tl) and BAlH4, AlGaH4, GaInH4, and InTlH4 stoichiometries via density functional theory (DFT) and ab initio quantum chemistry methods performing Coalescence Kick (CK) global minimum search and AdNDP chemical bonding analysis. We found that all global minimum structures possess multicenter electron bonds. The difference between the structures of X2H4 stoichiometry for boron and aluminum is much more significant than that between other pairs of Al–Ga, Ga–In, and In–Tl. The evolution of Group 13 hydride structure involves the gradual prevalence of classical 2c-2e bonds over multicenter bonds for heavier elements. The found structural features of the heterogeneous hydrides are in total agreement with those of homogeneous hydrides and with the trends common for the periodic table that allows us to investigate the structural evolution of Group 13 hydrides more completely.

Global Minimum Search and Bonding Analysis of Tl2Hx and Tl3Hy (x=0–6; y=0–5) Series

“…Also, a conformational search for homogeneous hydrides of X 2 H 4 (X=BÀ Tl) stoichiometries and heterogeneous hydrides of AlBH 4 , GaAlH 4 , InGaH 4 , and TlInH 4 stoichiometries demonstrated that the structures of Tl and In hydrides slight differ from those of Al and Ga and differ dramatically from those of B. [32] In the current work, we aimed to provide an extensive conformational search for thallium hydrides of Tl 2 H x and Tl 3 H y stoichiometries (x = 0-6; y = 0-5) to explore and identify Global Minimum (GM) geometries and low-lying isomers via Coalescence Kick method, which has proven to be effective for the investigation of small and medium-sized clusters. [31,[33][34][35] We performed stoichiometry-by-stoichiometry investigation of structural evolution of thallium hydrides and compared some of them with those of indium hydrides.…”

“…Based on the conformational search of indium hydrides, [31] one would expect the prevalence of non‐classical structures where thallium tends to save its lone pair and even investigation of aromatic thallium hydride clusters. Also, a conformational search for homogeneous hydrides of X 2 H 4 (X=B−Tl) stoichiometries and heterogeneous hydrides of AlBH 4 , GaAlH 4 , InGaH 4 , and TlInH 4 stoichiometries demonstrated that the structures of Tl and In hydrides slight differ from those of Al and Ga and differ dramatically from those of B [32] …”