Mechanism for Forming B,C,N,O Rings from NH sub(3)BH sub(3) and CO sub(2) via Reaction Discovery Computations

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 120; no. 8; pp. 1135 - 1144
• Main Authors: Li, Maxwell W, Pendleton, Ian M, Nett, Alex J, Zimmerman, Paul M
• Format: Journal Article
• Language: English
• Published: 03.03.2016
• Subjects: Bonding; Carbon dioxide; Clusters; Computation; Computer programs; Formations; Graphene; Oxides
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/acs.jpca.5b11156

This study employs computational reaction finding tools to probe the unique biphilic reactivity between ammonia-borane (AB) and CO sub(2). The results show that sequential reactions involving multiple equivalents of AB and CO sub(2) can lead to the formation of stable nonplanar B,C,N,O-heterocycles (Cy-BCN). Cy-BCN is shown to emerge through boron-oxygen bond formation, hydroboration, dative bond formation, and single- or double-hydrogen transfers. The most kinetically facile reactions (computed at the coupled cluster singles and doubles with perturbative triples (CCSD(T)) level of theory) result from polarized nitrogen-boron double bonds whereas thermodynamic stability results from formation of covalent boron-oxygen bonds. An important structure, HCOOBHNH sub(2) (DHFAB), contains both of these features and is the key intermediate involved in generation of Cy-BCN. Crucially, it is shown that favorable boron-oxygen bond formation results in production of Cy-BCN species that are more stable than polyaminoboranes. These types of reaction intermediates could serve as building blocks in the formation of B,N-codoped graphene oxide (BCN).