Here we report relativistic electronic structure calculations employing all-electron density functional theory (DFT) including scalar and spin-orbit interaction, on the multimetallic sandwich compound [Pd-3(C7H7)(2)X-3](1-) (X = Cl- (1), Br- (2), and I- (3)), which can be considered as a [Pd3X3](3-) fragment flanked by two ring-ligands [(C7H7)(2)](2+). The calculations suggest that the [Pd3X3](3-)-ligand interaction is mainly arising from electrostatic contributions, where the formally zerovalent Pd atoms allows backdonation of charge from the halide X1- atoms to the [(C7H7)(2)](+2) ligands, resulting in a net charge of about +0.4 for each Pd atoms that decreases from 1 to 3. The electronic delocalization estimated via the NICS indexes and the ELF function allows us to describe a significant stabilizing sigma-aromaticity at the center of the Pd-3 triangle, which decreases from [Pd3Cl3](3-) to [Pd(3)l(3)](3) (1 to 3) due to the softer character of the iodine counterpart, that donates extra charge to the ligands. The calculated electronic transitions via TD.DFT are in reasonable agreement with the experimental data obtained in CH2Cl2 solution, indicating that the most intense transition involves a core-centered [Pd3X3](3) transition toward the [(C7H7)(2)](2+) ligands, with mainly X1- character in the former molecular spinor that is responsible for the variation of the observed lambda(max) according to the variation of X1-.