Highly accurate CCSD(T) homolytic Al–H bond dissociation enthalpies – chemical insights and performance of density functional theory

We obtain gas-phase homolytic Al–H bond dissociation enthalpies (BDEs) at the CCSD(T)/CBS level for a set of neutral aluminium hydrides (which we refer to as AlHBDE dataset). The BDEs in this dataset differ by much 79.2 kJ mol−1, with (H2B)2Al–H having lowest BDE (288.1 mol−1) and (H2N)2Al–H largest (367.3 mol−1). These results show that substitution least one –AlH2 or –BH2 substituent exerts far greatest effect modifying compared monomeric H2Al–H (354.3 To facilitate quantum chemical investigations large hydrides, which use rigorous methods such W2w may not be computationally feasible, assess performance 53 density functional theory (DFT) functionals. find DFT does strictly improve along rungs Jacob’s Ladder. best-performing from each rung Ladder are (mean absolute deviations given parentheses): GGA B97-D (6.9), meta-GGA M06-L (2.3), global hybrid-GGA SOGGA11-X (3.3), range-separated CAM-B3LYP (2.1), hybrid-meta-GGA ωB97M-V (2.5) double-hybrid mPW2-PLYP B2GP-PLYP (4.1