Insights into the Factors Controlling the H–H Bond Cleavage Reactions by Five-Membered G13/P (G13 = Group 13 Element) and B/G15 (G15 = Group 15 Element) Frustrated Lewis Pairs

Abstract

The origins of reaction barriers and reactive activities for H2 activation reactions by five-membered cyclic G13/P-Rea (G13 = group 13 element) and B/G15-Rea (G15 = group 15 element) frustrated Lewis pair (FLP) molecules were explored using the density functional theory [B3LYP-D3­(BJ)/def2-TZVP]. Our theoretical examinations suggest that all G13/P-Rea FLP-type molecules are energetically feasible to undergo the H2 activation reaction from kinetic and thermodynamic viewpoints, except for the case of Tl/P-Rea FLPs. However, in B/G15-Rea FLP-type systems, only the B/P-Rea FLP species can react with H2 to generate the adduct. The theoretical analysis based on energy decomposition analysis–natural orbitals for the chemical valence (EDA–NOCV) approach revealed that the singlet–singlet interaction (or donor–acceptor interaction) rather than the triplet–triplet interaction (or electron-sharing interaction) determines the bonding natures of saddle points. The frontier molecular orbital theory and EDA–NOCV method demonstrated that the lone pair (LB) → σ*­(H2) interaction rather than the empty p-π orbital (LA) ← σ­(H2) interaction played a prominent role in determining the bonding situations between H2 and G13/P-Rea and B/G15-Rea FLP-associated molecules. The theoretical findings based on the activation strain model indicate that the origin of the barriers for the reactions of G13/P-Rea and B/G15-Rea FLP-related molecules with H2 can be attributed to the atomic radius of the LA (G13) and LB elements (G15), respectively.

Insights into the Reactivity of the Ring-Opening Reaction of Tetrahydrofuran by Intramolecular Group-13/P- and Al/Group-15-Based Frustrated Lewis Pairs

“…Moreover, the bonding situations in the present FLP system were studied by EDA and the natural orbitals for chemical valence (NOCV) − method, which can partition the total Δ E Orb term into pairwise contributions of the orbital interactions. Details of the EDA-NOCV − method, which decomposes the bond energy in several well-defined terms, can be found elsewhere. , This approach has been proven to be a highly efficient tool for describing the bonding conditions in different types of systems. , EDA-NOCV computations were thus carried out at the zeroth-order regular approximation ZORA-B3LYP-D3­(BJ)/TZ2P//B3LYP-D3­(BJ)/def2-TZVP level, where the scalar relativistic effects were included by adopting the ZORA. All EDA-NOCV computations were performed using the Amsterdam density functional program package.…”

“… 67 , 68 This approach has been proven to be a highly efficient tool for describing the bonding conditions in different types of systems. 69 , 70 EDA-NOCV computations were thus carried out at the zeroth-order regular approximation ZORA 71 -B3LYP-D3(BJ)/TZ2P 72 //B3LYP-D3(BJ)/def2-TZVP level, where the scalar relativistic effects were included by adopting the ZORA. All EDA-NOCV computations were performed using the Amsterdam density functional 73 program package.…”

Computational insights into the reactivity for the [2+5] cycloaddition reactions of norbornene-linked group 14 element/P-based and Si/group 15 element-based frustrated Lewis pairs with benzaldehyde

“…This particular functional–basis set combination was chosen based on its good performance in our earlier analyses of the structures, bonding, and reactivity in related systems. 40 Frequency calculations were performed to determine whether the optimized geometries were minima or transition states on the potential energy surface.…”

Understanding the Reactivity of Combination Reactions of Intramolecular Geminal Group 13 Element/Phosphorus and Gallium/Group 15 Element Frustrated Lewis Pairs with CS2

“…25,26 Consequently, considerable effort has been devoted to explore the broad synthesis potential of this new type of catalyst 27−34 and reveal the details of the activation mechanism of some certain chemical bonds (such as H−H bonds). 35,36 Based on the results of many experimental observations, 25−34 atoms of LA and LB in the FLP-type molecule can improve the properties and reactivity of FLP-associated molecules because the unprecedented reactivity of FLPs is based on the presence of Lewis acidic and basic centers that interact simultaneously with the substrate. 27−34 This operation is important for the specific applications of these FLPs in the field of activation, coordination, or catalytic transformations.…”

“…In the past 15 years, a newly discovered concept of frustrated Lewis pairs (FLPs) introduced by Stephan et al, which can promote the activation of small molecules, has been recognized as a fundamental and novel strategy for designing environmentally friendly catalysts without metal participation. , Consequently, considerable effort has been devoted to explore the broad synthesis potential of this new type of catalyst − and reveal the details of the activation mechanism of some certain chemical bonds (such as H–H bonds). , Based on the results of many experimental observations, − chemists have begun to realize that the basic characteristics of FLP-mediated catalytic activity and preventing the formation of ordinary donor–acceptor bonds between Lewis acid (LA) and Lewis base (LB) are closely related to the spatial strain. In addition, chemists have discovered that careful adjustment of the central atoms of LA and LB in the FLP-type molecule can improve the properties and reactivity of FLP-associated molecules because the unprecedented reactivity of FLPs is based on the presence of Lewis acidic and basic centers that interact simultaneously with the substrate. − This operation is important for the specific applications of these FLPs in the field of activation, coordination, or catalytic transformations.…”