Every reaction Detail Matters: An in silico driven Step-by-Step Guide to understand the B2O3-Catalyzed CO2 to cyclic carbonates conversion

[Display omitted] •DFT analysis of B2O3-catalyzed CO2 cycloaddition, identifying key catalytic pathways.•Comparison of boron active sites in B2O3 shows AS1 is more efficient than AS2.•Mechanistic analysis using IBO, NAdO, and DIA reveals insights into catalytic activity. The catalytic conversion of carbon dioxide (CO2) to cyclic organic carbonates (COCs) via cycloaddition with epoxides offers a dual benefit of reducing CO2 emissions while producing valuable chemical products. In this detailed in silico study, we employ density functional theory (DFT) to meticulously investigate the mechanisms underlying the B2O3/n-NBu4Br-catalyzed cycloaddition of CO2 and epoxides, following a step-by-step approach according to the reaction details. We provide a comprehensive comparison of the non-catalyzed, n-NBu4Br alone, and B2O3/n-NBu4Br-catalyzed pathways, emphasizing two distinct active sites within the B2O3 framework: Site 1 (six-membered boroxol ring) and Site 2 (open chain configuration). Our computational analysis highlights that the Site 1-catalyzed reaction pathway is more favorable, featuring a lower overall energy barrier of 26.8 kcal/mol, compared to 32.5 kcal/mol for the Site 2-catalyzed pathway. Detailed intrinsic bond orbital (IBO), natural adaptive orbital (NAdO) and distortion-interaction analysis (DIA) reveal significant differences in bonding properties and energy interactions, elucidating why Site 1 exhibits superior catalytic activity over Site 2. These findings are corroborated by experimental observations, which indicate that ball milling B2O3 increases defect sites, thereby enhancing exposure of active sites Site 1 and improving catalytic performance. This study provides an in-depth understanding of how the intrinsic properties of boron active sites influence the catalytic efficiency of B2O3, offering valuable insights for the design and optimization of metal-free catalysts for CO2 conversion.