Thomas R. Burkholder

Reactions of boron atoms with molecular oxygen. Infrared spectra of BO, BO2, B2O2, B2O3, and BO−2 in solid argon

Boron atoms from Nd:YAG laserablation of the solid have been codeposited with Ar/O2 samples on a 11±1 K salt window. The product infrared spectrum was dominated by three strong 11B isotopic bands at 1299.3, 1282.8, and 1274.6 cm− 1 with 10B counterparts at 1347.6, 1330.7, and 1322.2 cm− 1. Oxygen isotopic substitution (16O18O and 18O2 ) confirms the assignment of these strong bands to ν3 of linear BO2. Renner–Teller coupling is evident in the ν2 bending motion. A sharp medium intensity band at 1854.7 has appropriate isotopic ratios for BO, which exhibits a 1862.1 cm− 1 gas phase fundamental. A sharp 1931.0 cm− 1 band shows isotopic ratios appropriate for another linear BO2 species; correlation with spectra of BO− 2 in alkali halide lattices confirms this assignment. A weak 1898.9 cm− 1 band grows on annealing and shows isotopic ratios for a BO stretching mode and isotopic splittings for two equivalent B and O atoms, which confirms assignment to B2O2. A weak 2062 cm− 1 band grows markedly on annealing and shows isotope shifts appropriate for a terminal–BO group interacting with another oxygen atom; the 2062 cm− 1 band is assigned to B2O3 in agreement with earlier work. A strong 1512.3 cm− 1 band appeared on annealing; its proximity to the O2 fundamental at 1552 cm− 1 and pure oxygen isotopic shift suggest that this absorption is due to a B atom–O2 complex.

Reactions of pulsed laser produced boron and nitrogen atoms in a condensing argon stream

Reactions of pulsed laser produced B and N atoms at high dilution in argon favored diboron species. At low laser power with minimum radiation, the dominant reaction with N2 gave BBNN (3Π). At higher laser power, reactions of N atoms contributed the B2N (2B2), BNB (2Σu+), NNBN (1Σ+), and BNBN (3Π) species. These new transient molecules were identified from mixed isotopic patterns, isotopic shifts, and ab initio calculations of isotopic spectra.

Infrared spectra of molecular B(OH)3 and HOBO in solid argon

Anhydrous B(OH)3 was pressed into a pellet and sublimed at room temperature under vacuum to give molecular B(OH)3 for argon matrix infrared study. The spectrum showed sharp fundamentals without the effect of hydrogen bonding observed in the solid. Fermi resonances were characterized for two fundamentals. The observed frequencies for B(OH)3 and the three deuterium substituted molecules are in agreement with values from self‐consistent field/double zeta plus polarization (SCF/DZP) calculations allowing for appropriate scale factors. The major thermal decomposition products from pulsed laser evaporation of B(OH)3 were H2O, B2O3, and HOBO. Molecular HOBO was characterized by a strong 2020 cm−1 fundamental, which was confirmed by SCF/DZP calculations.

Pulsed laser evaporation of boron/carbon pellets: Infrared spectra and quantum chemical structures and frequencies for BC2

Pulsed laser evaporation of pellets pressed from boron and graphite powder gave a new 1:4 doublet at 1232.5 and 1194.6 cm−1 in addition to the carbon cluster absorptions reported previously. The 1232.5 cm−1 band dominated boron‐10 experiments. The new bands increased as carbon cluster bands decreased with increasing B/C ratio in the pellet and with increasing laser power. Augmented coupled cluster and full‐valence complete active space SCF (CASSCF) calculations predict the global minimum BC2 structure to be an asymmetric triangle: however, the vibrationally averaged structure will be an isosceles triangle with a strong symmetric B–C2 stretching frequency near 1200 cm−1. The calculated boron‐10/boron‐11 frequency ratio (1.0323) is in excellent agreement with the observed ratio (1.0317), and confirms assignment of the 1194.6 cm−1 band to the BC2 ring. Calculations predict linear BCC to be less stable by 6.2±2 kcal/mol and to absorb in the 2000–2050 cm−1 range: the barrier towards rearrangement to the cyclic...

Matrix infrared detection of OBSO

Abstract Boron atoms codeposited with SO 2 in excess argon gave a strong product absorption at 2006.3 cm −1 , which exhibited isotopic shifts ( 10 B, 34 S, 18 O) appropriate for the BO stretching fundamental of the OBSO insertion product.