We started our investigation with the construction of an insilico library of triarylboranes using the strategy described below. Generally, we explored triarylboranes that seemed to be synthetically accessible using common procedures. Optimization of the gas-phase structures of the 54 boranes shown in Figure was accomplished using DFT calculations at the B97X-D/6-311+G(d,p)//B97X-D/6-31G(d,p) level. The 53 explored heteroleptic boranes B xy (x = 1-6, y = a-w) include two 2,6-F2-3,5-R2-C6H groups, and their core structures are classified as B 1 -B 6 depending on the R groups, i.e., B x (R) = B 1 (F), B 2 (Cl), B 3 (Br), B 4 (CF3), and B 5 (H), whereas B 6 includes 2,6-F2-3-Cl-C6H2 groups. With these core structures, we combined 23 aryl groups (a-w), and completed the construction of the borane library with the addition of B(C6F5)3. It should be noted that boranes B xa (x = 1-3, 5-6), B 1v , and B 1w were known before the construction of this library, and their reactivity in the hydrogenation of unsaturated molecules inspired us when designing the library molecules. In fact, B 1a has previously been employed for the catalytic reductive alkylation of aniline derivatives to generate active FLP species with THF, and thus, in-silico derivatization of B 1a was carried out via substitution of the meta and/or para H atoms in the 2,6-Cl2-C6H3 group with Cl, Br, CF3, OMe, OCF3 or C6F5 groups. We further conducted extensive in-silico derivatization of B 2a and B 3a , given that these boranes exhibit far superior catalytic activity than B 1a , B 6a , and B(C6F5)3 in the hydrogenation of N-heteroaromatics using a gaseous mixture of H2/CO/CO2/CH4. In these cases, we envisioned that the modulation of the intrinsic Lewis acidity of the triarylboranes, i.e., the energy levels of the LUMO, which includes the p orbital on the boron center, as well as the remote back-strain that influences the stability of the four-coordinated tetrahedral Lewis base-borane adducts. The introduction of 2,6-Br2-C6H3 (j) and its derivatives (k-r) into the B 2 core was also explored, as we expected an increase in the front strain that influences the accessibility of the Lewis bases to the boron centers. We subsequently obtained the theoretical parameters. We thought that the use of structural parameters obtained from the gas-phase optimization of B xy would not play a critical role in predicting the reactivity of the triarylboranes under the chosen conditions, given that no substantial differences were observed among them (Table ). Thus, we obtained the following energetic parameters: (i) the energy levels of the LUMOs [eV], which include the p orbitals on the boron atoms, (ii) the energy barriers (GH ‡ in kcal mol -1 ) for the heterolytic cleavage of H2 with the combination of B xy and THF, and (iii) the relative Gibbs energy values (Gw°) [kcal mol ] for the formation of the H2O-B xy adducts with respect to [H2O + B xy ]. These theoretical values are shown in Figure for some selected boranes. For parameter (ii), we have previously proposed that the heterolytic cleavage of H2 by FLPs should be involved in the ratedetermining event of the B 1a -catalyzed reductive alkylation of amines. For parameter (iii), H2O could be a potential quencher of the triarylborane catalysts via the formation of adducts followed by proto-deboronation. In this context, we envisioned that boranes B xy that exhibit larger Gw° and smaller GH ‡ values should show superior performance as Lewis acids for the generation of more active FLPs with ethereal components. It should also be mentioned here that we theoretically optimized a structure that included a sole imaginary frequency related to the H-H bond cleavage; however, to reduce the calculation costs, we performed an IRC calculation only for selected cases Next, we turned our attention to collecting experimental data for the reported triarylboranes (B xa , x = 1-3, 5, 6; B 1v ; B 1w ; B(C6F5)3) and newly synthesized boranes (B 1f ; B 2y , y = b, c, e; B 3y , y = b, c, s); the latter compounds were used to analyze the influence of the derivatization of the 2,6-Cl2-C6H3 structure. We obtained the turnover frequency (TOF in h -1 ; Figure ) as an experimental parameter calculated based on the yield of 3aa from the reductive alkylation of amino acid 1a with benzaldehyde (2a) and H2 in the presence of 5 mol% B xy under the shown conditions as a model reaction (Figure ). The design of this model reaction is based on the potential of B 1a to produce 3aa in approximately 50% yield after 6 h (i.e., TOF = 1.67 h -1 ), as this consideration allows for a clearer evaluation of the positive and negative effects of structural derivatization during the optimization of B xy .