Ionization energies for the actinide mono- and dioxides series, from Th to Cm: theory versus experiment.

The results of a computational study with multiconfigurational quantum chemical methods on actinide monoxides (AnO) and dioxides (AnO(2)) for An = Th, Pa, U, Np, Pu, Am, and Cm, are presented. First and second ionization energies were determined and compared with experimental values, when available. The trend along the series is analyzed in terms of the electronic configurations of the various species.

A theoretical study of the ground state and lowest excited states of PuO0/+/+2 and PuO(2)0/+/+2.

The ground and excited states of neutral and cationic PuO and PuO2 have been studied with multiconfigurational quantum chemical methods followed by second order perturbation theory, the CASSCF/CASPT2 method. Scalar relativistic effects and spin-orbit coupling have been included in the treatment. As literature values for the ionization energy of PuO2 are in the wide range of approximately 6.

Bond length and bond order in one of the shortest Cr-Cr bonds.

Multiconfigurational quantum chemical calculations on the R-diimines dichromium compound confirm that the Cr-Cr bond, 1.80 A, is among the shortest Cr(I)-Cr(I) bonds. However, the bond between the two Cr atoms is only a quadruple bond rather than a quintuple bond.

Large differences in secondary metal-arene interactions in the transition-metal dimers ArMMAr (Ar = terphenyl; M = Cr, Fe, or Co): implications for Cr-Cr quintuple bonding.

Quantum mechanical calculations, using both CASPT2 and DFT methods, for the model systems (MeMMMe, PhMMPh, (MeMMMe)(C6H6)2, Ar(S)MMAr(S), Ar (#)MMAr(#); M = Cr, Fe, Co; Ar(S) = C6H4-2(C6H5), Ar(#) = C6H3-2,6(C6H3-2,6-Me2)2) are described. These studies were undertaken to provide a multireference description of the metal-metal bond in the simple dimers MeMMMe and PhMMPh (M = Cr, Fe, Co) and to determine the extent of secondary metal-arene interaction involving the flanking aryl rings of the terphenyl ligands in quintuply bonded Ar'CrCrAr' (Ar' = C6H3-2,6(C6H3-2,6-Pr(i)2)2). We show that in the Cr-Cr species the Cr-arene interaction is a feeble one that causes only a small weakening of the quintuple bond.