Comparative study of geometric and QTAIM-based differences between X-H•••Y intramolecular charge-inverted hydrogen bonds, M1•••(H-X) agostic bonds and M2•••(η2-XH) σ interactions (X = Si, Ge; Y = Al, Ga; M1 = Ti, Co; M2 = Mn, Fe, Cr)

General conclusions on geometric and QTAIM-based differences and similarities between X-H center dot center dot center dot Y intramolecular charge -inverted hydrogen bonds (IMCIHBs), M1 center dot center dot center dot(H-X) agostic bonds and M-2 center dot center dot center dot(eta(2)-XH) sigma interactions (X = Si, Ge; Y = Al, Ga; M-1 = Ti, Co; M-2 = Mn, Fe, Cr) are formulated. In particular we show that IMCIHBs feature significantly smaller covalent character as indicated, for example, by lower values of the electron density computed at BCPH center dot center dot center dot Y and lower values of delta(H,M). Some topological differences between IMCIHBs and the other interactions are found. Among others, it is shown that in agostic bonds and sigma interactions nuclear attractors of H and M are more located in the H center dot center dot center dot M space and that bond paths tracing the X-H bond are in many instances significantly curved toward RCP, whereas, on the contrary, the corresponding bond paths tracing X-H in systems featuring IMCIHB are straight. Also the influence of the Si -> Ge replacement was carefully studied, increasing the current state of knowledge on the chemistry of germanium. (C) 2016 Elsevier B.V. All rights reserved.