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The structure and substitution energies of dichlorotris(triphenylphosphine)ruthenium(II) complex, [RuCl
2
(PPh
3
)
3
], was computed with ten different methods at the density functional theory level using a composition of basis sets. The PBE0 functional led to the best description of bond lengths, while the MN12-L functional yielded the best results for bond angles. For calculation of the Ru-P bond dissociation energies, the best results were obtained with the M06-L functional. The nature of the Ru-P bond was discussed in terms of donation and back-donation as well as in terms of the steric versus covalent contributions to the bonding. In the square pyramidal structure, the apical Ru-P bond is considerably tighter than the basal Ru-P bonds. This is due to an interaction of the apical PPh
3
ligand with a high d character orbital on the Ru atom, favouring back-donation, leading to a short Ru-P distance and strong bonding energy. Additionally, we also investigated the equilibrium structures and mechanism for the substitution of one of the PPh
3
group by the piperidine molecule. The equilibrium between the several species involved in the substitution process indicates that addition of the piperidine molecule to [RuCl
2
(PPh
3
)
3
] followed by elimination of a PPh
3
unity is the pathway with lower energy.