β-Diketonate Coordination: Vibrational Properties, Electronic Structure, Molecular Topology, and Intramolecular Interactions. Beryllium(II), Copper(II), and Lead(II) as Study Cases.

Nine metal complexes formed by three symmetric β-diketonates (, acetylacetonate (), 1,1,1,3,3,3-hexafluoro-acetylacetonate (), and 2,2,6,6-tetramethylheptane-3,5-dionate ()) and three metal ions (with three different coordination geometries, , Be - tetrahedral, Cu - square planar, and Pb - "swing" square pyramidal) were investigated. The study combines structural analyses, vibrational spectroscopic techniques, and quantum chemical calculations with the aim of bridging crystal structure, electronic structure, molecular topology, and far-infrared (FIR) spectroscopic characteristics. The effect of intramolecular interactions on the structural, electronic, and spectroscopic features is the center of this study. The crystal structure of Be() is also reported and discussed for the first time. A complete review of the experimental IR spectra is offered; discrepancies in the assignments of some peaks are revealed among the published works. Anharmonic effects were considered for complexes; however, they were negligible for the FIR modes. A systematic comparison between computed and experimentally measured data allowed us to design an inexpensive, yet efficient computational protocol to investigate large polynuclear complexes.