AB INITIO STRUCTURES, VIBRATIONS, AND THERMOCHEMISTRY OF IO, $IO^{-}$, AND $IO^{+}$
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Date
1996
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Ohio State University
Abstract
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 $IO^{-}(^{1}\Sigma^{+})(\Delta_{f}H^{0}_{0} 109\pm 5)$ kJ/mol uncertainties are $2\sigma$ was obtained from ab initio energetics for the metathesis reactions $IO+Cl\rightarrow CIO^{+}+I^{-}$ and $IO^{-}Cl_{2}\rightarrow ClO+ICl$. 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 $^{a}$. The enthalpy of formation for IO $X^{2}\Pi_{3/2}(\Delta_{f}H^{0}_{0}=120\pm 5)$ kJ/mol was deduced from the calculated $(\Delta_{f}H^{0}_{0}(IO^{-})$ and the experimental electron affinity of measured by Gilles et al.. The enthalpy enthalpy of formation of $IO^{-}(^{3}\Sigma^{+})(\Delta_{f}H^{0}_{0}=1060\pm 5)$ 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 $D_{0}^{0}(IO)-167\pm 5)$ kJ/mol $D_{0}^{0}(IO)= 234 \pm 5$ kJ/mol and $D^{0}_{0}(IO^{+})=303\pm 5$ kJ/mol. JANAF style thermodynamic functions for IO, $IO^{-}$ and $IO^{-}$ from 0 to 1000 K are also tabulated.
Description
$^{a}$Guest Researcher
Author Institution: Physical and Chemical Properties Division, National Insititute of Standard and Technology
Author Institution: Physical and Chemical Properties Division, National Insititute of Standard and Technology