Characterization of the BNNO Radical

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Quantum Mechanics

Background:

• The electronic states and isomerization reactions of BNNO molecules are not fully understood.
• Investigating potential energy surfaces (PES) is crucial for predicting reaction pathways and product formation.

Purpose of the Study:

• To systematically investigate the cyclic, trans, and cis isomers of BNNO and their isomerization reactions on the doublet electronic states' potential energy surface (PES).
• To determine the relative stabilities, interconversion barriers, and dissociation energies of these isomers.
• To rationalize experimental observations regarding the formation of BNNO isomers from the B + NNO reaction.

Main Methods:

• Employed high-level ab initio quantum mechanical methods, including self-consistent field (SCF), complete active space SCF (CASSCF), coupled cluster with single and double excitations (CCSD), and CCSD(T).
• Utilized Dunning's correlation consistent polarized valence basis sets (cc-pVXZ and aug-cc-pVXZ) up to the quadruple zeta (QZ) level.
• Calculated fundamental vibrational frequencies using second-order vibrational perturbation theory (VPT2).

Main Results:

• All stationary points on the doublet PES were found to be within 19 kcal mol(-1) of the global minimum cyclic isomer.
• The energy differences and interconversion barriers between the cyclic, trans, and cis isomers were quantified.
• Dissociation energies for BNNO to B + NNO and BN + NO fragments were calculated for each isomer.
• Comparison with experimental vibrational frequencies revealed that the B + NNO reaction predominantly forms the trans isomer, which is not the global minimum.

Conclusions:

• The study provides a comprehensive theoretical investigation of BNNO isomers and their reaction dynamics.
• The formation of the trans isomer in the B + NNO reaction, despite not being the global minimum, is explained by detailed analysis of the reaction's potential energy surface.
• The theoretical predictions offer valuable insights for understanding the reactivity and stability of BNNO and related molecules.