Cerium can be stabilized in solution in a tetravalent form in the presence of nitrates, predominantly as ceric ammonium nitrate (CAN) assigned as a monomeric hexanitrate cerium structure. However, recent synchrotron X-rays and Raman spectroscopy have challenged this picture, and propose instead an unusual Ce−O−Ce dimeric linkage observed when CAN is dissolved in water.1 Conversely, tetravalent thorium and plutonium form dimers with a double μ2-OH bridge. To rationalize the formation of this dimeric species, we will scrutinize the structure, spectroscopy (Raman, infrared) and the bonding of this peculiar dimeric species, in particular with respect to f/d metal participation to the bridging interactions. The structures and vibrational spectra of various isomers of the cerium, thorium and plutonium dimer have been density functional theory methods. Natural bond orbital (NBO) and quantum theory of atoms-in-molecules (QTAIM) approaches have been used to analyze the nature of the μ2-O and μ2-OH bridging chemical bonds. The theoretical results will shed light on the relative preference of μ2-O single bridge with respect to μ2-OH double bridges.

Probing the bonding in dimers of tetravalent cerium and actinide homologues

255th National Meeting (2018)

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