Interaction of Th with H 0/-/+ : Combined Experimental and Theoretical Thermodynamic Properties.

High-level electronic structure calculations of the low-lying energy electronic states for ThH, ThH ^- , and ThH ⁺ are reported and compared to experimental measurements. The inclusion of spin-orbit coupling is critical to predict the ground-state ordering as inclusion of spin-orbit switches the coupled-cluster CCSD(T) ordering of the two lowest energy states for ThH and ThH ⁺ . At the multireference spin-orbit SO-CASPT2 level, the ground states of ThH, ThH ^- , and ThH ⁺ are predicted to be the ² Δ _3/2 , ³ Φ ₂ , and ³ Δ ₁ states, respectively. The adiabatic electron affinity is calculated to be 0.820 eV, and the vertical detachment energy is calculated to be 0.832 eV in comparison to an experimental value of 0.87 ± 0.02 eV. The observed ThH ^- photoelectron spectrum has many transitions, which approximately correlate with excitations of Th ⁺ and/or Th. The adiabatic ionization energy of ThH including spin-orbit corrections is calculated to be 6.181 eV. The natural bond orbital results are consistent with a significant contribution of the Th ⁺ H ^- ionic configuration to the bonding in ThH. The bond dissociation energies for ThH, ThH ^- , and ThH ⁺ using the Feller-Peterson-Dixon approach were calculated to be similar for all three molecules and lie between 259 and 280 kJ/mol.