A systematic computational study of organoactinide complexes of the form [LAnX]n+ has been carried out using density functional theory, the quantum theory of atoms in molecules (QTAIM) and Ziegler-Rauk energy decomposition analysis (EDA) methods. The systems studied feature L = trans-calixbenzenepyrrolide, An = Th(IV), Th(III), U(III) and X = BH4,
BO2C2H4, Me, N(SiH3)2, OPh, CH3, NH2, OH, F, SiH3, PH2, SH, Cl, CH2Ph, NHPh, OPh, SiH2Ph, PHPh2, SPh, CPh3, NPh2, OPh, SiPh3 PPh2, SPh. The PBE0 hybrid functional proved most suitable for geometry optimisations based on comparisons with available experimental data. An-X bond critical point electron densities, energy densities and An-X delocalisation indices, calculated with the PBE functional at the PBE0 geometries, are correlated with An-X bond energies, enthalpies and with the terms in the EDA. Good correlations are found between energies and QTAIM metrics, particularly for the orbital interaction term, provided the X ligand is part of an isoelectronic series and the number of open shell electrons is low (i.e. for the present Th(IV) and Th(III) systems).