Stability and donor-acceptor bond in dinuclear organometallics CpM1–M2Cl3 (M1, M2 = B, Al, Ga, In; Cp = η5–C5H5)

The geometries and stabilities of the dinuclear organometallics CpM 1 –M 2 Cl 3 (M 1 , M 2 = B, Al, Ga, In; Cp = η 5 -C 5 H 5 ) have been investigated by density functional theory (DFT) at M06 L/6-311G(d, p) levels. The nature of the donor–acceptor M 1 → M 2 bond was also studied based on the atoms in molecules (AIM) theory, energy decomposition analysis (EDA) and natural bond orbital (NBO) analysis. The results show that the electronegativity of the M atom determines the stability and covalent character of the dinuclear organometallics CpM 1 –M 2 Cl 3 . The compounds in which the M with larger electronegativity acts as the donor are more stable than in those in which it acts as the acceptor in the donor–acceptor bond, and the donor–acceptor bond has more covalent characteristics. The strength and polarity of the M 1 → M 2 donor–acceptor bond is determined by the periodicity of the M atom. When the period number of the M 1 atom is smaller than that of M 2 , the strength of the M 1 → M 2 bond is larger than that of the M 2 → M 1 bond. For homonuclear dinuclear organometallics, the polarity of the M–M bond increases with increasing atomic number of the M atom. For heteronuclear complexes, the polarity of the M 1 –M 2 bond for a given M 1 also increases in the sequence of M 2 = B, Al, Ga, and In. Graphic abstract Molecular graph and electron location function isosurfaces map of CpM 1 –M 2 Cl 3( small red spheres represent bond critical points)