Infrared spectra and structures of the Th(OH)2 and Th(OH)4 molecules

Abstract

Thorium atoms react with H₂O₂, H₂ + O₂ mixtures, and H₂O in excess argon to form the Th(OH)₂ and Th(OH)₄ molecules as minor and major products, respectively. The vibrational frequencies observed in the matrix infrared spectra are in excellent agreement with MP2 computed values, which confirms the identification of these highly ionic thorium hydroxide molecules. Our MP2 calculations converge to slightly bent and tetrahedral structures, respectively. This investigation reports the first evidence for pure actinide dihydroxide and tetrahydroxide molecules.