Hydrolysis of Metal Dioxides Differentiates d-block from f-block Elements: Pa(V) as a 6d Transition Metal; Pr(V) as a 4f “Lanthanyl”

Abstract

V . Computed potential energy profiles agree with the experimental results, and furthermore indicate that acetone unexpectedly induces de-hydrolysis and displaces two H2O from (H2O)VO(OH)2 + to yield (acetone)2VO2 + . Structures and energies for several M V , as well as for Th IV and U VI , indicate that hydrolysis is governed by involvement of valence f versus d orbitals in bonding: linear f-element dioxides are more resistant to hydrolysis than bent d-element dioxides. Accordingly, for early actinides, hydrolysis of Th IV is characteristic of a 6d-block transition metal; hydration of U V and U VI is characteristic of 5f actinyls; and Pa V is intermediate between 6d and 5f. The praseodymium oxide cation Pr V O2 + is assigned as an actinyl-like lanthanyl with properties governed by 4f bonding.

Hydrolysis of Small Oxo/Hydroxo Molecules Containing High Oxidation State Actinides (Th, Pa, U, Np, Pu): A Computational Study

“…The results for Th IV O 2 are shown in Table at different levels of theory (new and previously reported) , and in Figure at the CCSD­(T)/aD-DK level. The current CCSD­(T)-DK results are consistent with our prior work on the hydrolysis of ThO 2 and that of others .…”

“… a aug-cc-pVDZ­(H,O)/cc-pVDZ-PP­(Th). b (aug-)­cc-pV n Z-DK3. c (aug-)­cc-pV n Z-PP from ref . d CCSD­(T)/CBS­(awCV n Z)/PW91+SO + ECP correction from ref . …”

“…The hydrolysis of ThO 2 is characteristic of transition-metal oxide hydrolysis, with the energy to form the hydrolysis product, Th­(OH) 4 , almost 3 times more exothermic than for the formation of the hydration product (H 2 O) 2 ThO 2 (Table ). The complete hydrolysis of PaO 2 (OH) to Pa­(OH) 5 is preferred over the hydration product, (H 2 O) 2 PaO 2 (OH), although the hydrolysis product is not as exothermic as for Th supporting our previous results for PaO 2 + that the formal Pa­(V) oxidation state is more transition-metal-like than actinide-like . For UO 3 , the hydrolysis product U­(OH) 6 and the hydration product (H 2 O) 3 UO 3 are essentially isoenergetic.…”

“…The complete hydrolysis of PaO 2 (OH) to Pa(OH) 5 is preferred over the hydration product, (H 2 O) 2 PaO 2 (OH), although the hydrolysis product is not as exothermic as for Th supporting our previous results for PaO 2 + that the formal Pa(V) oxidation state is more transition-metal-like than actinide-like. 73 For UO 3 , the hydrolysis product U(OH) 6 and the hydration product (H 2 O) 3 UO 3 are essentially isoenergetic. For NpO 3 , the hydration product (H 2 O) 3 NpO 3 is preferred over the hydrolysis product Np(OH) 6 .…”

Protactinium and Actinium Monohydrides: A Theoretical Study on Their Spectroscopic and Thermodynamic Properties

“…To overcome the difficulties in handling these elements, electronic structure calculations in combination with experimental studies can provide important insights into their bonding and reactivity. Although studies on the metal, diatomic, − complexes, , oxides, − and hydrolysis processes , containing the Pa atom have been reported in the literature, there is a lack of information about the electronic structure of the metal atom and properties involving its anions. Previous ab initio calculations include the relativistic configuration interaction (RCI) calculations of the Pa anion binding energies where the valence electrons were correlated.…”