DFT Study on the Reed Diethylaluminum Cation-like System: Structure and Bonding in Et2Al(CB11H6X6) (X = Cl, Br)

Electronic and molecular structure has been investigated in the diethylaluminum cation-like system Et2Al(CB11H6X6) (1, X = Cl; 2, X = Br) and neutral compounds AlX3 (X = Cl, Br, Me, C6H5) with DFT B3LYP and BP86 levels of theory. The calculated geometries of Et2Al(CB11H6X6) (1, X = Cl; 2, X = Br) are in excellent agreement with those determined experimentally by X-ray crystallography. The Al-X bond distances 2.442, 2.445 (angstrom) in 1 and 2.579, 2.589 (angstrom) in 2 are longer than those expected for single bonds based on covalent radius predictions (Al-Cl = 2.15 (angstrom) and Al-Br = 2.32 (angstrom)) and those observed for bridged Al-X-Al bonds (2.21 (angstrom) in Al2Cl6, 2.33 (angstrom) in Al2Br6) and are close to sum of ionic radii of Al3+ and X- (Al-Cl = 2.35 (angstrom) and Al-Br = 2.50 (angstrom)).