On the stability of non‐conventional π‐complexes between Ni+and toluene, phenyl‐silane and phenyl‐germane

Abstract

AbstractThe complexes between Ni+and toluene, phenylsilane, and phenylgermane were investigated through the use of high‐level density functional theory (DFT) methods. Both harmonic vibrational frequencies and optimized geometries were obtained at the B3LYP/6‐311G(d,p) and B3LYP/6‐311+G(2df,2p) levels of theory. These results show that at the highest level considered in this work, and in contrast with what was found before for Cu+, the complexes in which Ni+interacts specifically with only one pair of carbon atoms of the aromatic ring collapse to theconventional π‐complexes. However, similarly to Cu+, non‐conventional complex in which the metal ion interacts with theorthocarbon of the aromatic ring and with one of the hydrogen atoms of the XH3(X = Si, Ge) substituent group, through a typical agostic‐type interaction are very stable. Nevertheless, whereas for Cu+these agostic‐type complexes are not only the global minima of the potential energy surface but the dominant species in the gas phase, for Ni+they are slightly less stable than the conventional π‐complexes. Agostic‐type complexes exhibit infrared spectra that are markedly different from those of the conventional π‐complexes, and therefore they could be easily identified using this spectroscopic technique. Copyright © 2006 John Wiley & Sons, Ltd.