Beryllium-9 quadrupole coupling constants and rotational correlation times of bis(acetylacetonato)beryllium(ii) in acetonitrile at different temperatures

Abstract

The ⁹Be quadrupole coupling constants, eQq/h, in 2.15 mol kg⁻¹ [Be(acac)₂]–CD₃CN (acac⁻ = pentane-2,4-dionate ion) at eight temperatures between 240 and 309 K were determined by the dual spin probe technique. The value of eQq/h was 348 kHz independent of temperature. By using the eQq/h value, the rotational correlation time of the complex in CH₃CN at infinite dilution, τ_r^∞, was evaluated from the ⁹Be relaxation rate measured in 12.7 mmol kg⁻¹ [Be(acac)₂]–CH₃CN. The τ_r^∞ thus obtained was proportional to η₀/T, where η₀ is the viscosity of the solvent at temperature T. The proportional constant was compared with that of [Co(acac)₃] in CH₃CN, which was determined elsewhere. We deduce that [Be(acac)₂] interacts with acetonitrile molecules more weakly than [Co(acac)₃].