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Issue 11, 2003
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The importance of agostic-type interactions for the binding energies of Ni+ to saturated and α,β-unsaturated alkanes, silanes and germanes

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Abstract

The gas-phase interaction of H3C–CH2–XH3 and H2C[double bond, length as m-dash]C(H)XH3 (X = C, Si, Ge) with Ni+ has been investigated through the use of high-level density functional theory methods. The structures of the corresponding Ni+ complexes were optimized at the B3LYP/6-311G(d,p) level of theory. Final energies were obtained in single-point B3LYP/6-311+G(2df,2p) calculations. In all cases, the most stable complexes are stabilized through agostic-type interactions between the metal cation and the hydrogen atoms of the XH3 group. Only for propene is the conventional π-complex the global minimum of the potential energy surface. These agostic-type linkages can be viewed as three-center bonds resulting from electron-donor interactions between σ bonding orbitals of the neutral and the empty s orbital of the metal and back-donation from pairs of valence electrons of the metal into the corresponding σ* antibonding orbitals of the neutral. As a consequence, these bonds are particularly stable for Si- and Ge-containing compounds, because of the high electron-donor ability of the XH3 group when the heteroatom is Si or Ge. Vinylsilane and vinylgermane lead to non-conventional complexes in which the metal bridges the Cα atom of the C[double bond, length as m-dash]C double bond and one of the hydrogen atoms of the XH3 group. In contrast with the behavior predicted when the reference acid is Cu+, Si- and Ge-derivatives, both saturated and unsaturated, bind Ni+ more strongly than propane and propene, respectively. Ni+ binding energies are systematically greater than Cu+ binding energies and the bond activation effects observed upon Ni+ attachment are sizably larger than those found upon Cu+ association.

Graphical abstract: The importance of agostic-type interactions for the binding energies of Ni+ to saturated and α,β-unsaturated alkanes, silanes and germanes

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Publication details

The article was received on 15 May 2003, accepted on 24 Jun 2003 and first published on 04 Sep 2003


Article type: Paper
DOI: 10.1039/B305532A
New J. Chem., 2003,27, 1657-1664

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    The importance of agostic-type interactions for the binding energies of Ni+ to saturated and α,β-unsaturated alkanes, silanes and germanes

    I. Corral, O. Mó and M. Yáñez, New J. Chem., 2003, 27, 1657
    DOI: 10.1039/B305532A

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