Relative and absolute bond dissociation energies of sodium cation–alcohol complexes determined using competitive collision-induced dissociation experiments

Absolute (R1OH)Na+–(R2OH) and relative Na+–(ROH) bond dissociation energies are determined experimentally by competitive collision-induced dissociation of (R1OH)Na+(R2OH) complexes with xenon in a guided ion beam mass spectrometer. The alcohols examined include ethanol, 1-propanol, 2-propanol, n-butanol, iso-butanol, sec-butanol, and tert-butanol, which cover a range in Na+ affinities of only 11 kJ/mol. Dissociation cross sections for formation of Na+(R1OH) + R2OH and Na+(R2OH) + R1OH are simultaneously analyzed with a model that uses statistical theory to predict the energy dependent branching ratio. The cross section thresholds thus determined are interpreted to yield the 0 K (R1OH)Na+–(R2OH) bond dissociation energies and the relative 0 K Na+–(ROH) binding affinities. The relative binding affinities are converted to absolute 0 K Na+–(ROH) binding energies by using the absolute bond energy for Na+–C2H5OH determined previously in our laboratory as an anchor value. Comparisons are made to previous experimental and theoretical Na+–(ROH) thermochemistry from several sources. The absolute (R1OH)Na+–(R2OH) bond dissociation energies were also calculated using quantum chemical theory at the MP2(full)/6-311+G(2d,2p)//MP2(full)/6-31G(d) level (corrected for zero-point energies and basis set superposition errors) and are generally in good agreement with the experimentally determined values.

Graphical abstractAbsolute (R1OH)Na+–(R2OH) and relative and absolute Na+–(ROH) bond dissociation energies are determined experimentally by competitive collision-induced dissociation of (R1OH)Na+(R2OH) complexes with xenon in a guided ion beam mass spectrometer.Figure optionsDownload full-size imageDownload high-quality image (26 K)Download as PowerPoint slide