Investigation of Chemical Bonding in In Situ Cryocrystallized Organometallic Liquids.

This Communication presents the crystal structure of the organometallic complexes (η4 -1,3-cyclohexadiene) iron tricarbonyl (I) and (methyl cyclopentadienyl) manganese tricarbonyl (II) which are both liquid at room temperature. The crystal structures were determined using a state-of-the-art in situ cryocrystallization technique. The bonding features were elucidated using topological analysis of charge density in the framework of quantum theory of atoms in molecules (QTAIM) and theoretical charge density analysis (multipolar refinement), to decipher the metal-carbonyl, metal-olefin and metal-carbocyclic ligand interactions in these complexes. Complex I displayed a simultaneous interplay of a "synergic effect" (σ-donation and π-back-bonding in the metal and an end-on coordinated carbonyl interaction) as well as consistency with the Dewar-Chatt-Duncanson (DCD) model (metal and side-on coordinated π-ligand interactions).