Silatranes and their Tricyclic Analogs

Pestunovich, V. A.; Kirpichenko, S. V.; Воронков, М. Г.

doi:10.1002/9780470682531.pat0186

Cited by 9 publications

(13 citation statements)

References 206 publications

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“…First, the intramolecular interactions of Si←N and Si←O types induce partial charges q − and q + on the Si and N(O) atoms, respectively. Note in this connection that the charge transfer from N to Si in related molecules of silatranes is approximately 0.2e . Second, a distinctive feature of the molecules of Series I–XII is a short distance d between the substituents (X, Y, Z) and the reaction centers localized within the Si−N and Si−O fragments.…”

Section: Resultsmentioning

confidence: 88%

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Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Кузнецова

Egorochkin

Negrebetsky

et al. 2012

J of Physical Organic Chem

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The intramolecular complexes containing coordination bonds Si←N or Si←O are distinguished for their stereochemical nonrigidity resulting in interconversion between isomers, that is, ligand‐site exchange. The influence of the substituents bound to the silicon atom on the free energies of activation for ligand exchange ΔG≠ of specific interest is poorly understood. In this work, the literature data on substituent influence on the energies ΔG≠ for 13 series of the complexes have been considered, using the correlation analysis. On the basis of the obedience of the energies ΔG≠ to the linear free energy relationship, it has been established for the first time that the ΔG≠ values depend not only on the inductive and resonance effects but also on the polarizability and steric effects of substituents. The reason for the occurrence of the polarizability effect is the appearance of excess charges on Si and N (or O) atoms as a result of intramolecular coordination consisting in the charge transfer from the donor center (N or O atom) to the acceptor one (Si atom). In some series the contribution of the polarizability or steric effect to the overall change in ΔG≠ because of the influence of substituents is a maximum. An understanding of these effects may give a better insight into the mechanism of nucleophilic substitution, involving organoelement compounds. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 88%

“…Considerable evidence indicates that tetravalent silicon is capable of extending its valence shell and forming stable derivatives with more than four bonds (see, e.g., Refs ). We will cover hypervalent organosilicon compounds formed by intramolecular coordination.…”

Section: Introductionmentioning

confidence: 99%

Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Кузнецова

Egorochkin

Negrebetsky

et al. 2012

J of Physical Organic Chem

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“…The Si–N distance in 20 is 2.117 Å and thus is essentially longer than the 2.023 Å in a related chlorosilatrane. 32 Nevertheless, this distance is within the range (2.0–2.2 Å) of a transannular interaction between Si and N. 33 No interaction between Si and N is observed in 22 ( Figure S36 in the Supporting Information) and 23 ( Figure 8 ), where the Si–N distance is 3.711 Å for 22 and 3.709 Å for 23 due to the influence of the Ln–N coordination. Both Ln–Si complexes crystallize in monoclinic space groups, 22 in C 2 and 23 in C 2/ c .…”

Section: Resultsmentioning

confidence: 95%

Using Functionalized Silyl Ligands To Suppress Solvent Coordination to Silyl Lanthanide(II) Complexes

et al. 2017

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The reaction of the potassium 1,3-trisilanediide Me2Si[Si(Me3Si)2K]2 with SmI2 and YbI2 was found to give the respective disilylated complexes Me2Si[Si(Me3Si)2]2Sm·2THF and Me2Si[Si(Me3Si)2]2Yb·2THF. Desolvation of coordinated solvent molecules in these complexes made their handling difficult. However, using a number of functionalized silanide ligands, complexes with a diminished number or even no coordinated solvent molecules were obtained ((R3Si)2Ln(THF)x (x = 0–3)). The structures of all new lanthanide compounds were determined by X-ray single-crystal structure analysis. NMR spectroscopic analysis of some Yb–silyl complexes pointed at highly ionic interactions between the silyl ligands and the lanthanides. This bonding picture was supported by DFT calculations at the B3PW91/Basis1 level of theory. Detailed theoretical analysis of a disilylated Eu(II) complex suggests that its singly occupied molecular orbitals (SOMOs) are very close in energy to the ligand silicon lone pairs (HOMO), and SQUID magnetometry measurements of the complex showed a deviation from the expected behavior for a free Eu(II) ion, which might be due to a ligand–metal interaction.

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“…Highly polar C 3 symmetrical intramolecular silicon complexes XSi(OCH 2 CH 2 ) 3 N, i.e., silatranes ( XS ), are ideal candidates for such investigation. It is pertinent to note that the existence of a labile dative Si ← N bond in XS molecules (Figure ) predetermines their unique structure, unusual physical and chemical properties, as well as rich and various biological activities. − Mainly for this reason, the interest has not waned in the problem of the electronic structure of XS , its dependence on internal and external factors, and in the properties of the Si ← N coordination. ,− …”

Section: Introductionmentioning

confidence: 99%

“Outlaw” Dipole-Bound Anions of Intra-Molecular Complexes

et al. 2020

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Using the example of silatranes XSi(OCH 2 CH 2 ) 3 N (X = Me, H, F, Cl), XS, it was found that the effect of the dipolebound (DB) electron on the cage intramolecular complexes does not fit into the standard views. Upon the transition from XS to the DB anions XS − , the unusual shortening of the internuclear Si•••N distance is always observed. For X = Cl, it is equal to 0.15 Å, which is a record length for all DB anions known from the literature. The formation of DB anions with the cage structure has principal features, controlled not only by the "critical" value of the dipole moment (μ > 2.5 D), but also by a geometric factor, such as the degree of pyramidality of the N(CH 2 ) 3 moietythe positive end of the molecular dipole of XS. It was a surprise that the effect of the substituent X on the extent of the structural rearrangement in the process XS → XS − cannot be explained using the values of the electron detachment energy of XS − or the initial strength of the coordination Si ← N bond in XS. The unique sensitivity of the silatrane geometry to the addition of an excess electron is governed by the rate of increase of their dipole moment with the shortening of the dative Si ← N contact. The conclusions drawn are supported by the high-accuracy CCSD and CCSD(T) calculations and the experimental (RET-PES) data. There is no real reason to doubt that the peculiarities of the formation of DB anions of XS − can also be characteristic of many hundreds of their structural analogues XM(YCH 2 CH 2 ) 3 N (

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Silatranes and their Tricyclic Analogs

Abstract: General Introduction Silatranes Silatrane Analogs Acknowledgments

Cited by 9 publications

References 206 publications

Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Using Functionalized Silyl Ligands To Suppress Solvent Coordination to Silyl Lanthanide(II) Complexes

“Outlaw” Dipole-Bound Anions of Intra-Molecular Complexes

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