Infrared and Ultraviolet Spectra of Diborane(6): B₂H₆ and B₂D₆

Abstract

We recorded absorption spectra of diborane(6), B2H6 and B2D6, dispersed in solid neon near 4 K in both mid-infrared and ultraviolet regions. For gaseous B2H6 from 105 to 300 nm, we report quantitative absolute cross sections; for solid B2H6 and for B2H6 dispersed in solid neon, we measured ultraviolet absorbance with relative intensities over a wide range. To assign the mid-infrared spectra to specific isotopic variants, we applied the abundance of (11)B and (10)B in natural proportions; we undertook quantum-chemical calculations of wavenumbers associated with anharmonic vibrational modes and the intensities of the harmonic vibrational modes. To aid an interpretation of the ultraviolet spectra, we calculated the energies of electronically excited singlet and triplet states and oscillator strengths for electronic transitions from the electronic ground state.

Nuclear quantum and H/D isotope effects on three‐centered bonding diborane: Path integral molecular dynamics simulations

“…It would seem that the mechanism was similar to the competing quantum effects observed in earlier studies in liquid water, where it was explained that quantum H 2 O and classical H 2 O (or quantum D 2 O) generated similar average O─O distances due to the opposite quantum effects acquired from the hydrogen bond/angle fluctuations. In addition, the structures from the CLMD and PIMD simulations of B 2 H 6 slightly deviated from its structure and the experiment by Peng et al to a very low temperature, since our simulations were performed at 298.15 K.…”

“…The structure of B 2 H 6 involves bridging and contains two three‐centered bonds (as presented in Figure ). There are two stable isotopic variants of diborane: 80% and 20% for 11 B and 10 B, respectively . The most abundant species of diborane is 11 B 2 H 6 .…”

“…There are two stable isotopic variants of diborane: 80% and 20% for 11 B and 10 B, respectively . The most abundant species of diborane is 11 B 2 H 6 . It can be converted into higher boranes by moderate heat depending on further reaction conditions by heat‐treated diboranes (ie, B 5 H 11 , B 4 H 10 , B 5 H 9 , B 10 H 14 and some others via indirect routes).…”

“…Subsequently, Price reported on the characteristics of the normal modes of a bridge model of diborane, which agreed very well with the interpretation of the electron diffraction results in terms of the bridge model. Detailed information on the spectroscopy of diborane was obtained by both experimental and theoretical studies . Recently, Peng et al reported the study of IR and UV spectra of diborane for both B 2 H 6 and B 2 D 6 in solid neon, in gaseous and solid phases.…”

“…Detailed information on the spectroscopy of diborane was obtained by both experimental and theoretical studies . Recently, Peng et al reported the study of IR and UV spectra of diborane for both B 2 H 6 and B 2 D 6 in solid neon, in gaseous and solid phases. Their study revealed the sufficiently quantitative intensity of the UV and IR spectrum, as well as the relevant theoretical calculations, according to their vibrational modes and intensities.…”