The proton affinity of HOBr

The proton affinity (PA) of HOBr is determined to be 161.5 +/- 1.0 kcal/mol (298.15 K). The single and double coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T), was used in conjunction with large spdfg atomic natural orbital basis sets to arrive at this value. The PA of HOBr is 7.0 kcal/mol larger than a recent prediction for HOCl. The most stable form of protonated HOBr is H2OBr+ with HOBrH+ determined to be 17.4 +/- 1.0 kcal/mol (298.15 K) higher in energy.