The structure of iron pentacarbonyl, Fe(CO)(5), solvated in various solvents has been investigated by FTIR measurements and density functional theory (DFT) calculations. The primary focus rested on the solvation properties of iron pentacarbonyl in aromatic solvents ranging from benzene to increasingly fluorinated derivatives. While, in the gas phase, most iron pentacarbonyl molecules have D-3h symmetry, about 60-90% of them have C-2v or C-4v symmetry in aromatic solvents at room temperature. The C-4v structure exists in the gas phase as a transition state during a Berry pseudorotation. In solution, this transition state is stabilized by interaction with a solvent molecule located trans to the apical ligand of Fe(CO)(5)(similar toC(4v)), forming a weakly interacting solute-solvent complex. Benzene, for instance, does not coordinate to the iron with its pi-system but with one of its aryl hydrogens. The equilibrium populations of conformers with various symmetries were investigated through (i) calculations of the Gibbs free energy for D-3h, C-2v, and C-4v conformers of Fe(CO)(5) after DFT structure refinement of the Fe(CO)(5)-solvent complex, (ii) experimental FTIR data in combination with theoretical IR absorption intensity values from our DFT calculations, and (iii) entirely experimental temperature-dependent FTIR data. The configuration population measurements relied on an absorption band around 2113 cm(-1), which was assigned to a CO-stretching vibration of C-2v and C-4v symmetry. While this stretching mode is exclusively Raman active in D-3h symmetry, it becomes increasingly IR active as the symmetry of Fe(CO)(5) is broken by solvation. The absorption band is about a factor 800 weaker than the ones around 2000 cm(-1), which are usually considered in IR spectroscopy of CO vibrations. We demonstrate that, despite its small intensity, this mode carries quantitative spectroscopic information about the conformer distribution.