Relativistic effects for the reaction Ubq + 6 CO = Ubq (CO)6 or Ubq (OC)6:Prediction of the existence, atomization energy, and isomerization energy of the isomers Ubq (CO)6 and Ubq (OC)6 of element Ubq ( Z=124, eka-uranium)

TL;DR

This study uses relativistic quantum calculations to predict the stability, energies, and structures of superheavy element Ubq compounds, revealing significant relativistic effects on their properties.

Contribution

First ab initio relativistic calculations of atomization and isomerization energies for Ubq(CO)6 and Ubq(OC)6, highlighting relativistic effects on superheavy element compounds.

Findings

Relativistic effects increase isomerization energy by ~3.78 eV.

Ubq(CO)6 is more stable than Ubq(OC)6 by ~7 eV at the DF level.

Relativistic calculations predict formation and stability of both isomers.

Abstract

Our ab initio all-electron relativistic Dirac*Fock (DF) calculations for the octahedral (Oh) Ubq(CO)6 and Ubq(OC)6 predict atomization energies (Ae) of 50.25 (47.93) and 43.43 (44.88 ) eV, respectively where the corresponding non-relativistic calculated Ae's are given in parenthesis. Our calculated DF and NR isomerization energies (E iso) for Ubq (CO) 6 = Ubq (OC) 6 are 6.83 and 3.05 eV, respectively. Our calculated DF (NR) energy for the reaction Ubq + 6CO = Ubq (CO)6 is -4.31 (-4.30) eV, while the energy of the isomeric reaction Ubq + 6CO = Ubq(OC)6 is 2.52 ( -1.25 ) eV, respectively. The relativistic effects increase the Eiso of Ubq (CO)6 by ~3.78 eV , decrease the Ubq-C bond distance by 0.12 angstroms and have a negligible effect on the C-O bond distance as expected. These are the first results of relativistic effects for isomerztion energy and atomization energy of the superheavy Ubq (CO)6 and Ubq(OC)6. The bond distances Ubq-C and Ubq-O optimized at the DF level of theory for Ubq(CO)6 and Ubq(OC)6 are 2.572 and 2.559 angstroms, while the corresponding optimized bond distances Ubq-C and Ubq-O at the NR level of theory are 2.691 and 3.616 angstroms, respectively. Both our DF and NR calculations clearly predict the formation of both the isomers Ubq(CO)6 and Ubq(OC), and the former is predicted to be more stable at the DF level of theory by ~7 eV than the latter.No such calculations have been reported before for systems of such superheavy elements.