Periodic Trends within Actinyl(VI) Nitrates and Their Structures, Vibrational Spectra, and Electronic Properties

A series of actinyl(VI) nitrate salts of the form MAnO(2)(NO3)(3), where M = NH4+ K+, Rb+, Cs+, and Me4N+ and AnO(2)(2+) = U, Np, Pu, and AnO(2)(NO3)(2)(H2O)(2)& BULL;H2O, and the uranyl tetranitrates M2UO2(NO3)(4) have been synthesized from aqueous solution and their structures determined using single-crystal X-ray diffraction. Together, these complexes represent an isostructural series of actinide complexes among the salts crystallized with the same charge-compensating cation and have been studied using vibrational spectroscopy including Raman and Fourier-transform infrared. Periodic trends in both the structural properties of these complexes and their vibrational spectra are presented and discussed, in particular the invariant nature of the O equivalent to An equivalent to O asymmetric stretching frequencies observed across the actinyl series. Electronic structure calculations were performed at a variety of levels of theory to aid in the interpretation of the vibrational data and to correlate trends in the data with the underlying electronic properties of these molecules.

Automated summary

A series of actinyl(VI) nitrate salts and uranyl tetranitrates have been synthesized and their structures determined using X-ray diffraction. Vibrational spectroscopy was used to study the structural properties and periodic trends in the vibrational spectra of these complexes, revealing the invariant nature of the O equivalent to An equivalent to O asymmetric stretching frequencies across the actinyl series. Electronic structure calculations were performed to interpret the vibrational data and correlate trends with the underlying electronic properties of these molecules.