Pentacoordination at Fluoro-Substituted Silanes by Weak Lewis Donor Addition

Schoeller, Wolfgang W.; Rozhenko, Alexander

doi:10.1002/(sici)1099-0682(200002)2000:2<375::aid-ejic375>3.0.co;2-2

Cited by 21 publications

(17 citation statements)

References 41 publications

(3 reference statements)

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“…For example, early work suggested that tetrafluorosilane was bound to ammonia more tightly than unsubstituted silane [ 63 ]. This conclusion was confirmed in later calculations confined to Si [ 64 , 65 ] as well as in the other works that extended to complexes containing heavier tetrel atoms [ 31 , 66 ], and is consistent with our own findings above.…”

Section: Resultssupporting

confidence: 92%

Comparison between Tetrel Bonded Complexes Stabilized by σ and π Hole Interactions

2018

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The σ-hole tetrel bonds formed by a tetravalent molecule are compared with those involving a π-hole above the tetrel atom in a trivalent bonding situation. The former are modeled by TH4, TH3F, and TH2F2 (T = Si, Ge, Sn) and the latter by TH2=CH2, THF=CH2, and TF2=CH2, all paired with NH3 as Lewis base. The latter π-bonded complexes are considerably more strongly bound, despite the near equivalence of the σ and π-hole intensities. The larger binding energies of the π-dimers are attributed to greater electrostatic attraction and orbital interaction. Each progressive replacement of H by F increases the strength of the tetrel bond, whether σ or π. The magnitudes of the maxima of the molecular electrostatic potential in the two types of systems are not good indicators of either the interaction energy or even the full Coulombic energy. The geometry of the Lewis acid is significantly distorted by the formation of the dimer, more so in the case of the σ-bonded complexes, and this deformation intensifies the σ and π holes.

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Section: Resultssupporting

confidence: 92%

Comparison between Tetrel Bonded Complexes Stabilized by σ and π Hole Interactions

2018

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“…The tetrel family of atoms, headed by C and Si, also appear able to serve in this capacity [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] . These sorts of bonds appear to be important in a number of processes including chemical reactions, molecular recognition, and the structure of materials [41][42][43][44][45] .…”

Section: Introductionmentioning

confidence: 99%

Systematic Elucidation of Factors That Influence the Strength of Tetrel Bonds

2017

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Quantum calculations are used to examine the properties of heterodimers formed by a series of tetrel-containing molecules with NH as universal Lewis base. TH was taken as a starting point, with T = C, Si, Ge, and Sn. The H atoms were replaced by various numbers of F atoms-THF, TFH, and TF-so as to monitor the effects of adding electron-withdrawing substituents. Unsubstituted TH molecules form the weakest tetrel bonds, only up to about 2 kcal/mol. The bond is strengthened when the H opposite NH is replaced by F, rising up to the 6-9 kcal/mol range. Another means of strengthening arises when the three peripheral H atoms of TH are replaced by F. The effect of the latter is heavily dependent on the nature of the T atom and is particularly noticeable for larger tetrels. The two sorts of fluorination patterns are cooperative, in that their combination in TF yields by far the most powerful tetrel bonding agent. The tetrel bond is strengthened as the T atom moves further down the periodic table column. The strongest bond amounts to 25.5 kcal/mol for SnF··NH. A number of features correlate with the binding energy, but only roughly. These properties include the charge transfer, the AIM bond critical point electron density, the molecular electrostatic potential, and the stretch of the T-X covalent bond upon complex formation.

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“…32 The Lewis acidity of the silane is increased with increasing of the number of fluorine atoms at silicon. 39 Similarly, the number of fluorine atoms at silicon in the series of (O-Si)chelated amides of carboxylic acids (C) influences significantly the amount of the intramolecular C O→Si bond formation. 32 An intramolecular P O→Si interaction in compound 4 is absent, showing that the Lewis acidity of silicon is less important.…”

Section: Resultsmentioning

confidence: 99%