Conciliatory Inductive Model Explaining the Origin of Changes in the η²-SiH Bond Length Caused by Presence of Strongly Electronegative Atoms X (X = F, Cl) in Cp(OC)₂Mn[η²-H(SiH_3–nX_n)] (n= 0–3) Complexes

Abstract

Using three theoretical methods, QTAIM, IQA, and NCI, we analyze an influence of halogen atoms X (X = F, Cl) substituted at various positions in the -SiH3-nXn group on the charge density distribution within the η(2)-SiH bond and on the SiH bond energies in Cp(OC)2Mn[η(2)-H(SiH3-nXn)] complexes and isolated HSiH3-nXn molecules. It is shown that shortening of the η(2)-SiH bond in Cp(OC)2Mn[η(2)-H(SiH3-nXn)] complexes should be considered as a normal inductive result of halogenation. This η(2)-SiH bond's compression may, however, be overcome by a predominant elongation resulting from a contingent presence of a halogen atom at position trans to the η(2)-SiH bond. This trans effect is particularly large for bulky and highly polarizable chlorine. Moreover, peculiar properties of the trans chlorine atom are manifested in several ways. To explain the origin of all the observed changes in both the length and the electron charge distribution of the η(2)-SiH bond in investigated Cp(OC)2Mn[η(2)-H(SiH3-nXn)] complexes a new model, called the Conciliatory Inductive Model, is being proposed.

J(Si,H) Coupling Constants of Activated Si–H Bonds

“…In contrast to the classical silyl hydride 7 , however, the Si–H interaction in 6 is not completely broken as revealed by the analysis of the noncovalent interaction (NCI) index (Figure ). − In the NCI index, two scalar fields are employed to localize attractive and repulsive interaction domains: the electron density, ρ­( r ), and the reduced density gradient (RDG, s ( r )) as defined in formula in atomic units Both scalar fields s ( r ) and ρ­( r ) are physical observable quantities and can be determined by high-resolution X-ray diffraction studies and subsequent modeling of the electron density distribution via multipolar refinements .…”

“…A similar scenario is observed for Mn−Si interaction in the manganese complex 2 in line with theoretical predictions for the model systems (CH 3 )CpMn(CO) 2 H(SiH 3−n Cl n ) 85 (n = 0− 3): the Mn−Si BCP is present in the experimental charge density analyses but it disappears by an artificial stretching of the Mn−Si separation by 0.005 Å. Apparently, in the charge density picture complexes 1−7 represent a continuum of electronic structures along a single reaction coordinate.…”

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

“…It is also to draw attention to the fact that a given group X acts on the RY unit not only through the π-electron delocalization effect, but also through the σ-electron induction effect, which in many cases can be even more visible. [2,7,[43][44][45][46][47][48][49] Moreover, some substituents can affect the rest of a molecule, especially the closest atom or the closest bond, through the proximity effect.…”

Strength of Si–H ⋯ B charge-inverted hydrogen bonds in 1-silacyclopent-2-enes and 1-silacyclohex-2-enes

“…For example, in case of Y being a transition metal, this interaction is called an agostic bond [10][11][12][13] or a σ interaction [12][13][14][15][16][17] depending on a specific situation, whereas if Y is an electron-deficient element (as, for example, boron), this type of interaction was called a "charge-inverted hydrogen bond" (CIHB) [11][12][13][18][19][20][21][22][23][24][25]. Therefore, the electron-deficient Si-H-B bridge (this term was being used by Wrackmeyer et al [1][2][3][4]) in investigated systems in fact represents one of the examples of intramolecular charge-inverted hydrogen bonds (IMCIHB).…”