ESR of the BS Molecule in Inert Matrices at 4°K

ESR spectra of ¹¹BS and ¹⁰BS molecules in their ground ²Σ⁺ states were measured while isolated in solid neon and argon matrices at 4°K. g tensors and hyperfine structure constants for interaction with ¹¹B and ¹⁰B were determined. In neon the magnetic parameters for ${}^{11}\mathrm{BS\; are}{\mathrm{\hspace{0.17em}g}}_{\parallel }{\text{=2.0016(1), g}}_{\perp }{\text{=1.9942(1), A}}_{\parallel }{(}^{11}\mathrm{B}\text{)= 853.3(3)\hspace{0.17em}}\mathrm{MHz},$ and $A_{\perp }{(}^{11}\mathrm{B}\text{)=766.7(3)\hspace{0.17em}}\mathrm{MHz}.$ Observation of weak ESR signals attributed to ³³S hfs yields ${\mathrm{|\hspace{0.17em}A}}_{\perp }{(}^{33}\mathrm{S}\text{)|=16 (2)\hspace{0.17em}}\mathrm{MHz}.$ The observed ${\mathrm{\Delta \; g}}_{\perp }$ is in excellent accord with the magnitude and sign of the spin‐doubling constant, γo, as derived from published gas phase optical data. A CNDO calculation of the ground state wavefunction for BS was made and used to compare calculated spin densities and g values with experimental values. A comparison of the chemical bonding in BS and BO is given.