Stable N-heterocyclic borylenes with promising ligand properties: a contribution from theory

Abstract

Density functional theory calculations predict that strongly π-electron donating functionalities such as ylidic groups can be used as an ideal structural motif for stabilizing the hitherto unknown neutral five-membered boron(I) carbenoids. The boron(I) carbenoids proposed in this study possess the highest singlet–triplet energy separation values (ΔE_S–T = 25.5–42.3 kcal mol⁻¹) known to date and are strongly nucleophilic in nature. In addition, the majority of these borylenes are found to be capable of activating a variety of enthalpically strong bonds such as C–H and C–F bonds, whose computed relatively lower energy barriers than experimentally evaluated systems such as cAAC confirm their potential in small molecule activation. In addition, the combined activation strain model–energy decomposition analysis (ASM-EDA) methodology was applied to quantitatively rationalize the different reactivity trends exhibited by the proposed borylenes.