Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - f-Orbital covalency in the actinocenes (An = Th-Cm)
T2 - multiconfigurational studies and topological analysis
AU - Kerridge, Andrew
PY - 2014
Y1 - 2014
N2 - The CASSCF methodology is used to calculate the ground state electron densities of a series of seven actinocenes, AnCOT(2) (An = Th-Cm, COT = eta(8)-C8H8). The multiconfigurational character of these complexes is found to be substantial and topological analysis of the electron density via the QTAIM approach is therefore chosen in order to investigate the electronic structure in more detail. Topological analysis reveals increased values of the electron density at the An-C bond critical point for An = Pa-Pu, suggesting enhanced covalent character in metal-ligand bonding for these complexes. In order to investigate the origins of this covalency, integrated one- and two-electron properties are evaluated. A trend for increased electronic charge, spin density and electron localisation on the An centre as one traverses the actinide series is found. The difference between atomic number and the electron localisation index is considered and found to correlate well with the expected oxidation state in these complexes, with a tendency towards trivalent character for the later actinides. Total and orbitally resolved delocalisation indices are evaluated, and increased electron delocalisation is found for the complexes containing Pa-Pu centres. It is shown that, while 5f contributions to covalency in these complexes are smaller in magnitude than 6d contributions, the variation in covalency is almost entirely accounted for by the variation in the 5f contribution.
AB - The CASSCF methodology is used to calculate the ground state electron densities of a series of seven actinocenes, AnCOT(2) (An = Th-Cm, COT = eta(8)-C8H8). The multiconfigurational character of these complexes is found to be substantial and topological analysis of the electron density via the QTAIM approach is therefore chosen in order to investigate the electronic structure in more detail. Topological analysis reveals increased values of the electron density at the An-C bond critical point for An = Pa-Pu, suggesting enhanced covalent character in metal-ligand bonding for these complexes. In order to investigate the origins of this covalency, integrated one- and two-electron properties are evaluated. A trend for increased electronic charge, spin density and electron localisation on the An centre as one traverses the actinide series is found. The difference between atomic number and the electron localisation index is considered and found to correlate well with the expected oxidation state in these complexes, with a tendency towards trivalent character for the later actinides. Total and orbitally resolved delocalisation indices are evaluated, and increased electron delocalisation is found for the complexes containing Pa-Pu centres. It is shown that, while 5f contributions to covalency in these complexes are smaller in magnitude than 6d contributions, the variation in covalency is almost entirely accounted for by the variation in the 5f contribution.
KW - COUPLED CASPT2 CALCULATIONS
KW - ELECTRONIC-STRUCTURE
KW - NATURAL-POPULATION
KW - SANDWICH COMPLEXES
KW - BASIS-SETS
KW - ACTINIDE
KW - DENSITY
KW - STATES
KW - ATOMS
KW - LIGANDS
U2 - 10.1039/c3ra47088a
DO - 10.1039/c3ra47088a
M3 - Journal article
VL - 4
SP - 12078
EP - 12086
JO - RSC Advances
JF - RSC Advances
SN - 2046-2069
IS - 24
ER -