The molecular structure of 1-fluorosilatrane

Pa̋rkányi, László; Hencsei, P.; Bihátsi, L.; Müller, Tibor

doi:10.1016/0022-328x(84)80270-3

Cited by 66 publications

(23 citation statements)

References 7 publications

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“…For a series of patterns in the same medium, the 15 15 N shielding constants do not decrease on increasing the I effect of the halogen but on increasing its atomic number 266 . This is in agreement with the X-ray detection of a shorter Si N bond in 1-chlorosilatrane 155 than in 1-fluorosilatrane 154 .…”

Section: Nmr Spectrasupporting

confidence: 90%

“…In silatranyl oxonium salts 36 the Si N bond is a record short value, 1.965Å 150 . However, despite a lower electronegativity of the substituent X, a shorter transannular bond is observed for 1-chlorosilatrane 38 (2.023Å 155 ) than in 1-fluorosilatrane 37 (2.042Å 154 ).…”

Section: Molecular Structurementioning

confidence: 57%

“…The mean length of the equatorial Si O bonds is about 1.66Å, compared to 1.65Å in alkoxysilanes. The Si N bond distance in crystals of most silatranes is in the range 1.965 2.240Å and the difference Fourier synthesis shows a high peak of electron density at the region of the transannular bond 154,157 . This bond is considerably shorter than the sum of the van der Waals radii (3.54Å) but certainly longer than a usual single Si N bond of 1.7 1.8Å.…”

Section: Molecular Structurementioning

confidence: 98%

“…1-Alkoxysilatranes 1-Fluorosilatrane (37) or its 3,7,10-trimethyl derivative (37a) are formed by the reaction of the corresponding 1-ethoxysilatranes (30, 30a) with concentrated HF in i-propanol at room temperature 69,154 …”

Section: -Hydroxysilatranementioning

confidence: 99%

See 3 more Smart Citations

Silatranes and Their Tricyclic Analogs

Pestunovich

Kirpichenko

Воронков

1998

PATAI'S Chemistry of Functional Groups

144

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Section: Nmr Spectrasupporting

confidence: 90%

Section: Molecular Structurementioning

confidence: 57%

Section: Molecular Structurementioning

confidence: 98%

Section: -Hydroxysilatranementioning

confidence: 99%

See 2 more Smart Citations

Silatranes and Their Tricyclic Analogs

Pestunovich

Kirpichenko

Воронков

1998

PATAI'S Chemistry of Functional Groups

144

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“…In any case, the 146.4 (ref. 10) and 143.4 pm (ref. 14) C-C single bond lengths found in X-ray experiments are not supported by theoretical calculations, and the corresponding ED result seems to be slightly short in the case of 1-fluor~silatrane.~…”

Section: Resultsmentioning

confidence: 99%

Ab initio molecular orbital study of 1‐fluorosilatrane

Csonka

Hencsei

1994

J Comput Chem

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The molecular geometry of 1-fluorosilatrane was optimized fully by restricted Hartree-Fock (HF) calculations using the 3-21G, 3-21G(d) and 6-31G(d) basis sets, with the aim of locating the positions of the local minima on the energy hypersurface. The optimized geometries were compared with available experimental (X-ray and ED) and semiempirical data. The ab initio calculations using polarized basis sets are in good agreement with those of previously reported semiempirical calculations, giving a slightly longer equilibrium Si-N distance (-256 pm) in the case of the endo minimum. However, the exo minimum predicted by the semiempirical methods is not supported. There was no experimental evidence for the existence of this ex0 minimum, and the present ab initio calculations suggest that it is highly unstable. There is considerable disagreement among the experimental results in the C-N and C-C bond lengths in various silatranes, their differences being as large as 13 pm. The present calculations predict that these differences may appear because the silatrane skeleton is flexible with low-energy, large-amplitude internal motions which introduce considerable uncertainties into the position of ring carbon atoms. 0 1994 by John Wiley & Sons, Inc.bond. Two basic forms of the structure are possible: the endo form, in which the lone pair of the nitrogen is directing toward the silicon and the Si-N distance is relatively short (Figs. 1 and 2), and the exo form, in which the Si-N distance is much longer T which have the MNDof and the nitrogen lone pair is pointing outward, away from the cage structure of the molecule. The aforementioned semiempirical methods, which did not consider the d orbitals, may be disadvantageous in describing the Si-N hansannular interaction. A b initio theory is known to give reasonably reliable geometry in most of the cases if polarized

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The structure of 1-chlorosilatrane: Anab initio molecular orbital and a density functional theory study

Csonka

Hencsei

1996

J. Comput. Chem.

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The molecular geometries of the 1‐chloro‐, 1‐fluoro‐, 1‐methyl‐, and 1‐hydrogenosilatranes were fully optimized by the restricted Hartree‐Fock (HF) method supplemented with 3‐21G, 3‐21G(d), 6‐31G(d), and CEP‐31G(d) basis sets; by MP2 calculations using 6‐31G(d) and CEP‐31G(d) basis sets; and by GGA‐DFT calculations using 6‐31G(d5) basis set with the aim of locating the positions of the local minima on the energy hypersurface. The HF/6‐31G(d) calculations predict long (>254 pm) and the MP2/CEP calculations predicted short (∼225 pm) equilibrium Si(SINGLE BOND)N distances. The present GGA‐DFT calculations reproduce the available gas phase experimental Si(SINGLE BOND)N distances correctly. The solid phase experimental results predict that the Si(SINGLE BOND)N distance is shorter in 1‐chlorosilatrane than in 1‐fluorosilatrane. In this respect the HF results show a strong basis set dependence, the MP2/CEP results contradict the experiment, and the GGA‐DFT results in electrolytic medium agree with the experiment. The latter calculations predict that 1‐chlorosilatrane is more polarizable than 1‐fluorosilatrane and also support a general Si(SINGLE BOND)N distance shortening trend for silatranes during the transition from gas phase to polar liquid or solid phase. The calculations predict that the ethoxy links of the silatrane skeleton are flexible. Consequently, it is difficult to measure experimentally the related bond lengths and bond and torsion angles. This is the probable origin of the surprisingly large differences for the experimental structural parameters. On the basis of experimental analogies, ab initio calculations, and density functional theory (DFT) calculations, a gas phase equilibrium (re) geometry is predicted for 1‐chlorosilatrane. The semiempirical methods predict a so‐called exo minimum (at above 310 pm Si(SINGLE BOND)N distance); however, the ab initio and GGA‐DFT calculations suggest that this form is nonexistent. The GGA‐DFT geometry optima were characterized by frequency analysis. © 1996 by John Wiley & Sons, Inc.

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The molecular structure of 1-fluorosilatrane

Cited by 66 publications

References 7 publications

Silatranes and Their Tricyclic Analogs

Silatranes and Their Tricyclic Analogs

Ab initio molecular orbital study of 1‐fluorosilatrane

The structure of 1-chlorosilatrane: Anab initio molecular orbital and a density functional theory study

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