Structure of the complex UCl4∙2DMF by vibrational infrared spectroscopy and density functional theory

Structural models are designed and spectral characteristics are computed based on DFT calculations for a complex of UCl4 with two molecules of DMF (UCl4∙2DMF). The calculations were carried out using a B3LYP hybrid functional in the LANL2DZ effective core potential approximation for the uranium atom and an allelectron basis set, cc-pVDZ, for all other atoms with partial force-field scaling. Two structural variants were found for the complex. The first structure is more stable, has Ci symmetry, and is characterized by trans arrangement of ligands. The energy of the second structure of C2 symmetry (with cis arrangement of ligands) is greater by 46 kJ/mol. The formation of the complex is shown to be accompanied by significant changes in the structure of UCl4. The obtained spectral characteristics are analyzed and compared with experimental data. The adequacy of the proposed models and the agreement between calculation and experiment are demonstrated.