Geometry- and QTAIM-Based Comparison of Intramolecular Charge-Inverted Hydrogen Bonds, M center dot center dot center dot(H-Si) 'Agostic Bond', and M center dot center dot center dot(eta(2)-SiH) sigma Interactions

摘要

Using large sets of systems having an intramolecular charge-inverted hydrogen bond (IMCIHB), M center dot center dot center dot(H-a-Si) "agostic bond" or M center dot center dot center dot(eta(2)-SiH) sigma interaction, we have compared both geometric and QTAIM-based topological parameters characterizing all these three types of interactions. It is shown that IMCIHBs can be distinguished from the other relevant interactions by the significantly less elongated Si-H bond. The other geometric parameters are not characteristic because they accept wide ranges of values in systems having either an M center dot center dot center dot(H-a-Si) "agostic bond" or M center dot center dot center dot(eta(2)-SiH) interaction. If,QTAIM-based results are investigated, then it is shown that an IMCIHB can be characterized by the position of the BCPH center dot center dot center dot M that is closer to the metal atom, whereas, quite the contrary, this BCP has been found to be closer to the agostic hydrogen in complexes having either M center dot center dot center dot(H-a-Si) or M center dot center dot center dot(eta(2)-SiH) interattions: Another difference is-in the curvature of the M center dot center dot center dot H bond path. If the M center dot center dot center dot H bond path tracing the M center dot center dot center dot(H-E) (E = Si, C), interaction. is curved, then this curvature appears near the agostic hydrogen a property particularly pronounced in M center dot center dot center dot(H-C) agostic bonds. Moreover, it has also been shown that an IMCIHB can be characterized by lower curvatures and, in general, lower values of the electron density computed at than at BCPs of either M center dot center dot center dot(H-a-Si) or M center dot center dot center dot(eta(2)-SiH) interactions. Importantly, IMCIHBs can be distinguished from the other two types of interactions on the basis of values of delocalization index, which are significantly lower for IMCIHBs. Other QTAIM based parameters have occurred to be not characteristic for IMCIHBs due to wide ranges of their values obtained for M center dot center dot center dot(H-a-Si) and M center dot center dot center dot(eta(2)-SiH) interactions. It has also been shown that the PBEO functional gives the best molecular structure in comparison with experimental data.