MATRIX-ISOLATION ESR AND THEORETICAL INVESTIGATIONS OF (BNB)-B-11-N-14-B-11 AND (BNB)-B-10-N-14-B-11 - LASER VAPORIZATION GENERATION

The BNB radical has been generated by the laser vaporization of solid boron nitride and isolated in neon, argon, and krypton matrices at 4 K for detailed electron spin resonance (ESR) investigations. These studies indicate that BNB is a significant vapor species above solid boron nitride. The ESR experimental results and theoretical calculations conducted at the CI level show that BNB has an X 2-SIGMA ground electronic state. Calculated nuclear hyperfine interactions (A tensors) for B-11 and N-14 agree closely with the experimental results. A population analysis of the calculated wave function is compared with valence region orbital characters obtained from the commonly applied free atom comparison method used to relate A values to electronic structure. The unpaired electron is located primarily in sp orbitals on each boron atom with only a small amount of spin density on nitrogen. The magnetic parameters for BNB were practically identical in the three different rare gas hosts. The neon results (MHz) at 4 K are g parallel-to = 2.0020 (4), g perpendicular-to = 2.0011 (3); (B-11), A perpendicular-to = 434 (1), A parallel-to = 485 (2); (N-14) \A parallel-to\ less-than-or-equal-to 3, \A perpendicular-to\ = 20 (1).