Knowledge Bank

Ab initio internuclear distances and anharmonic constants for IO, IO and $IO-$ were calculated at the CCSD(T) level using 6-311+G(3df, 2p) basis sets. The relaiability of the calculations was tested against the available experiemental values for IO and $IO-$. Electronic energies were also calculated at the CCSD(T) level using the 6-311+G(3df,2p) basis sets, Sadlej#### polarized basis sets (PBS), and Wadt and Hay#### effective core podential (ECP) basis sets at the experimental geometries and corrected by the experimental zero-point vibrational energies. The enthalpy of formation of the hypoiodite anion $IO-(1\Sigma +)(\Delta fH00109\pm 5)$ kJ/mol uncertainties are $2\sigma$ was obtained from ab initio energetics for the metathesis reactions $IO+Cl\to CIO++I-$ and $IO-Cl2\to ClO+ICl$. The reliability of the computational procedure was tested by performing analogous calculations for $BrO-$ and comparing the results with the accepted value for the enthalpy of formation . The enthalpy of formation for IO $X2\Pi 3/2(\Delta fH00=120\pm 5)$ kJ/mol was deduced from the calculated $(\Delta fH00(IO-)$ and the experimental electron affinity of measured by Gilles et al.. The enthalpy enthalpy of formation of $IO-(3\Sigma +)(\Delta fH00=1060\pm 5)$ was also derived from the present enthalpy of formation of IO and the experimental adiabatic ionization energy of IO $IO(IE-939.4\pm 41.7)$ measured by Zhang et al. The corresponding bond dissociation energiers are $D00(IO)-167\pm 5)$ kJ/mol $D00(IO)=234\pm 5$ kJ/mol and $D00(IO+)=303\pm 5$ kJ/mol. JANAF style thermodynamic functions for IO, $IO-$ and $IO-$ from 0 to 1000 K are also tabulated.