The crucial role of agostic interactions in the binding of Cu⁺ to alkanes, silanes and germanes in the gas phase

Article type: Research Article

Authors: Corral, Inés | Mó, Otilia | Yáñez, Manuel^{; 1}

Affiliations: Departamento do Química, C-9. Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain

Note: [1] [email protected].

Abstract: The gas-phase interactions of H3C-CH2-CH3, H2C=C(H)XH3 and HC≡C-XH3 (X=C, Si, Ge) with Cu+ have been investigated through the use of B3LYP/6-311+G(2df,2p) calculations. The most stable complexes are stabilized through agostic interactions between the metal cation and the hydrogen atoms of the XH3 group. Only when the neutral presents a C≡C triple bond the conventional π-complexes are slightly more stable than those exhibiting agostic interactions. The nature of these non-conventional bonds is analyzed in terms of the topology of the charge density and second order orbital interactions. The strength of these bonds increases with the hydride character of the XH hydrogens explaining the fact that while propene and the Si- and Ge-containing analogs have similar Cu+ binding energies, ethylsilane and ethylgermane are predicted to bind Cu+ much more strongly than propane. Concomitantly, a significant weakening of the X-H linkages involved in the bond reflected in a very large red shifting of the X-H stretching frequency is systematically observed.

Keywords: Cu+-complexes, agostic interactions, binding energies, non-conventional bonds

DOI: 10.3233/JCM-2002-23-416

Journal: Journal of Computational Methods in Sciences and Engineering, vol. 2, no. 3-4, pp. 411-416, 2002