Bonding Analysis of the Trimethylenemethane (TMM) Complexes [(eta(6)-C6H6)M-TMM] (M = Fe, Ru, Os), [(eta(5)-C5H5)M-TMM] (M = Co, Rh, Ir), and [(eta(4)-C4H4)M-TMM] (M = Ni, Pd, Pt)

作者：Mousavi Masoumeh; Frenking Gernot^*

来源：Organometallics, 2013, 32(6): 1743-1751.

DOI：10.1021/om301163w

Quantum chemical calculations using gradient corrected density functional theory at the BP86/def2-TZVPP level have been carried out for the sandwichlike trimethylenemethane complexes of group 8 (eta(6)-C6H6)M-TMM (BzM-TMM), where M = Fe, Ru, Os, group 9 (eta(5)-C5H5)M-TMM (CpM-TMM), where M = Co, Rh, Ir, and group 10, (eta(4)-C4H4)M-TMM (CbM-TMM), where M = Ni, Pd, Pt. The nature of the metal-TMM bonding has been investigated with charge and energy decomposition analyses. The geometry optimization of the complexes gives sandwichlike structures where the terminal carbon atoms of the TMM ligands have significantly longer distances to the metal than to the central carbon. The calculated bond dissociations energies D-e of the TMM ligand are between 89.9 and 153.0 kcal/mol. The intrinsic interaction energies Delta E-int and the D-e values for the heavier group 8 and group 9 elements become larger for the heavier atoms in the order BzFe-TMM %26lt; BzRu-TMM %26lt; BzOs-TMM and CpCoTMM %26lt; CpRh-TMM %26lt; CpIr-TMM, respectively. The group 10 elements exhibit a V-shaped trend for Delta E-int and the De values with the sequence CbPd-TMM %26lt; CbNi-TMM %26lt; CbPt-TMM. The analysis of the bonding situation shows that the dominant orbital interactions come from the degenerate pi interactions between the singly occupied degenerate pi orbitals of the metal fragment and the TMM ligand. The degenerate pi orbital of TMM has coefficients only at the terminal atom. In agreement with the shape of the orbitals, the EDA-NOCV method suggests that the metal-TMM bonding takes place mainly between the terminal carbon atoms and the metal while the sigma bonding between the central carbon atom and the metal is rather weak. In contrast, the AIM analysis gives a bond path only between the metal atom and the closer central carbon atom but not to the more distant carbon atoms. This clearly shows that the AIM analysis does not faithfully represent the strongest pairwise interactions between the atoms in a molecule. The EDA-NOCV and the NBO methods agree that the TMM ligand in the complex carries only a small partial charge, which may be negative or positive.

• 出版日期2013-3-25