• charge density;
  • transition metal;
  • comparative study;
  • topological analysis;
  • bond critical points.

An accurate experimental charge density study at 100 K of Mn2(CO)10 [bis(pentacarbonylmanganese)(Mn—Mn)] has been undertaken. A comparison with previously reported structural determinations reveals no evidence for significant Mn—Mn bond lengthening between 100 and 296 K. The nature of the metal–metal and metal–ligand atom interactions has been studied by topological analysis using the Atoms in Molecules (AIM) approach of Bader [(1990), Atoms in Molecules: a Quantum Theory.Oxford: Clarendon Press]. An analysis of the density ρ(r), the Laplacian of the density ∇2ρ(rb) and the total energy densities H(rb) at the bond critical points is used to classify all the chemical bonds as covalent in nature. The results are compared qualitatively and quantitatively with previous charge density studies on this molecule and DFT calculations at the 6-311+G* B3LYP level. The topological properties of the theoretical and experimental densities are in close agreement.