Photoelectron spectroscopy and thermochemistry of the peroxyacetate anion.
The 351.1 nm photoelectron spectrum of the peroxyacetate anion, (CH(3)C(O)OO(-)) was measured. Analysis of the spectrum shows that the observed spectral features arise almost exclusively from transitions between the trans-conformer of the anion and the X(2)A'' and A (2)A' states of the corresponding radical. The electron affinity of trans-CH(3)C(O)OO is 2.381+/- 0.007 eV and the term energy splitting of the A (2)A' state is 0.691 +/- 0.009 eV, in excellent agreement with two prior values [Zalyubovsky et al. J. Phys. Chem. A 107, 7704 (2003); Hu et al. J. Phys. Chem. 124, 114305/1 (2006); Hu et al. J. Phys. Chem. 110, 2629 (2006)]. The gas-phase acidity of trans-peroxyacetic acid was bracketed between the acidity of acetic acid and tert-butylthiol at Delta(a)G(298)(trans-CH(3)C(O)OOH)=1439 +/- 14 kJ mol(-1) and Delta(a)H(298)(trans-CH(3)C(O)OOH)=1467+/-14 kJ mol(-1). The acidity of cis-CH(3)C(O)OOH was found by adding a calculated energy correction to the acidity of the trans-conformer; Delta(a)G(298)[cis-CH(3)C(O)OOH] = 1461 +/- 14 kJ mol(-1) and Delta(a)H(298)[cis- CH(3)C(O)OOH]=1490+/-14 kJ mol(-1). The O-H bond dissociation energies for both conformers were determined using a negative ion thermodynamic cycle to be D(0)[trans- CH(3)C(O)OOH]=381+/-14 kJ mol(-1) and D(0)[cis- CH(3)C(O)OOH]=403+/-14 kJ mol(-1). The atmospheric implications of these results and relations to the thermochemistry of peroxyacetyl nitrate are discussed briefly.
JILA, University of Colorado and the National Institute of Standards and Technology and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0440, USA.
Stephanie M
SM
Villano
Nicole
N
Eyet
Scott W
SW
Wren
G Barney
GB
Ellison
Veronica M
VM
Bierbaum
W Carl
WC
Lineberger