Experimental and Theoretical Study of the Transannular Intramolecular Interaction and Cage Effect in the Atrane Framework of Boratrane and 1-Methylsilatrane

Korlyukov, Alexander A.; Lyssenko, Konstantin А.; Antipin, M. Yu.; Kirin, V. N.; Chernyshev, E. A.; Knyazev, S. P.

doi:10.1021/ic010842e

Cited by 86 publications

(31 citation statements)

References 33 publications

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“…The limited literature on computational studies on silatranes is due to the large size of these molecules which restricts largely these studies to semi empirical methods, but a few reports using ab initio methods have been appeared in the last decade [27][28][29][30][31]. Initially, quantum chemical calculations of 3 were performed by using semiempirical methods (AM1, PM3, PM3MM and MNDO) but the accuracy of these methods was found insufficient to describe transannular N ?…”

Section: Theoretical Studiesmentioning

confidence: 99%

Synthesis and reactivity of novel 3-isothiocyanatopropylsilatrane derived from aminopropylsilatrane: X-ray crystal structure and theoretical studies

Singh

Puri

Kaur

et al. 2010

Journal of Organometallic Chemistry

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Section: Theoretical Studiesmentioning

confidence: 99%

Synthesis and reactivity of novel 3-isothiocyanatopropylsilatrane derived from aminopropylsilatrane: X-ray crystal structure and theoretical studies

Singh

Puri

Kaur

et al. 2010

Journal of Organometallic Chemistry

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“…The differences between the calculated and experi mental bond lengths of Si-O and Si-N can partially be attributed to thermal motion in a crystal and poor resolu tion in a standard X ray diffraction experiment. Indeed, a high precision X ray diffraction study of 2 (2θ max = 90°) 19 demonstrated that the bonds Si-O are elongated by 0.02 Å as compared to those in an experiment carried out with the conventional resolution (2θ max = 55°). 20 Table 2.…”

Section: Resultsmentioning

confidence: 99%

Chemical bonding in the crystal structure of 1-hydrosilatrane

et al. 2009

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A study has been made of the crystal and molecular structure of 1 hydrosilatrane HSi(OCH 2 CH 2 ) 3 N. The quantum chemical calculations of its crystal structure have been carried out. According to an estimate of the energy, the coordination bond N→Si is by 5 kcal mol -1 stronger than that in the crystal of 1 methylsilatrane. The charge values calcu lated within the framework of the topological analysis of the electron density demonstrate that the electron density of the coordination bond N→Si is primarily transferred to the region of the equatorial bonds Si-O and, to a lesser extent, to the bond Si-H. On going from the isolated molecule of 1 hydrosilatrane to its crystal, the interatomic distance N-Si decreases, mainly owing to the weak intermolecular interaction C-H…O.Key words: silatranes, 1 hydrosilatrane, X ray diffraction study, quantum chemical calcu lations, N→Si bond energy, density functional theory, basis sets of plane waves.As surprising as it may seem, the molecular and crystal structure of the parent compound of a broad family of silatranes, viz., 1 hydrosilatrane or silatrane, HSi(OCH 2 CH 2 ) 3 N (1), 1-4 has not been studied. This stems from the fact that so far the preparation of single crystals of 1 pos sessing high diffraction quality has failed. At the same time, the molecular structure of this compound, the most straightforward and convenient method of synthesis of which was suggested by one of us as early as 40 years ago, 5 attracted great interest of researchers. It was established by IR spectroscopy that the frequency and integral inten sity of the Si-H bond vibrations in molecule 1 (and, consequently, the distribution of electron density in the axial fragment N→SiH) depends on the polarity (dielec tric constant ε) of the solvent and temperature. 6 The electron diffraction and quantum chemistry meth ods allowed the study of the structure of molecule 1 in the gas phase. 7 It was found that a longer bond N→Si in an individual molecule of 1 (2.406 Å) (as compared to that in the structure we determined in the crystal) has an inter mediate value between the corresponding lengths of bonds N→Si in the molecules of 1 methylsilatrane (2) 8 and 1 fluorosilatrane (3) 9 (2.453 and 2.324 Å, respectively). Therefore, on the basis of the length of the bond N→Si molecule 1 is closer to 2 rather than to 3. This indicates the proximity of the values of the interaction energies of * Dedicated to academician A. I. Konovalov on his 75th birthday. the nitrogen and silicon atoms in the former two mol ecules. The bond length N→Si in molecule 1 calculated with the B3LYP/6 311G(d) and MP2 basis set amounts to 2.335 Å (see Ref. 10) and 2.351 Å (see Ref. 7), respec tively. As to the lengths of the bonds N-C, O-C, Si-O, and C-C, they are approximately the same as in mol ecules 2 and 3. In molecule 1 the silicon atom is shifted from the equatorial plane of three oxygen atoms surround ing it in the direction opposite to the nitrogen atom, the angle N-Si-O is smaller than 90°, while the angle Si-N-C is larger than 90°. ...

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“…43 It was proposed to treat the bonds with positive Laplacian and negative electronic energy density as belonging to intermediate type. 42 However, in the case of silatranes and germatranes classification based on the sign of the electronic energy density seems to be somewhat incorrect. Indeed, the data listed in Table 14 show that the electronic energy density for the M←N bond is nearly zero.…”

Section: Resultsmentioning

confidence: 99%

The molecular and electronic structure features of silatranes, germatranes, and their carbon analogs

et al. 2006

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Molecular geometries of fifty six metallatranes N(CH 2 CH 2 Y) 3 M-X and fifty six carbon analogs HC(CH 2 CH 2 Y) 3 M-X (M = Si, Ge; X = H, Me, OH, F; Y = CH 2 , O, NH, NMe, NSiMe 3 , PH, S) were optimized by the DFT method. Correlations between changes in the bond orbital populations, electron density ρ(r), electron density laplacian ∇ 2 ρ(r), |λ 1 |/λ 3 ratio, electronic energy density E(r), bond lengths, and displacement of the central atom from the plane of three equatorial substituents and the nature of substituents X and Y were studied. As the number of electronegative substituents at the central atom increases, the M←N, M-X, and M-Y bond lengths decrease, while the M←N bond strength and the electron density at critical points of the M←N, M-X, and M-Y bonds increase. An increase in electronegativity of a substituent (X or Y) is accompanied by a decrease in the ionicities of the other bonds (M-X, M-Y, and M←N) formed by the central atom (Si, Ge). A new molecular orbital diagram for bond formation is proposed, which takes into account the interaction of all five substituents at the central atom (M = Si, Ge) in atrane molecules.Recently, metallatranes N(CH 2 CH 2 Y) 3 M-X (com pounds with intramolecular interaction M←N) have at tracted particular attention of researchers owing to their unique properties. 1-5 For instance, silatranes are less re active in the reactions of nucleophilic substitution at sili con compared to their tetracoordinate analogs. 3 A nitro gen atom involved in intramolecular interaction remains inert to electrophiles, e.g., methyl iodide and tetracyano ethylene. 3 Besides, silatranes and germatranes exhibit a broad spectrum of biological activities, which makes these compounds promising for being used in medicinal chem istry. 6,7 It is believed that the biological activity of silatranes and germatranes is due to a weak transannular interaction; therefore, the emphasis is placed on the stud ies of the nature of the M←N bond in these compounds. 6,7 At present, transannular interaction is mainly studied by X ray analysis. This method was used in studies of a large number of silatranes and germatranes with substituents X and Y of the same type. Because of this, the available X ray analysis data are insufficient for correlating the effects of substituents X and Y and the parameters of transannular interaction. It is significant that the metal-donor intramolecular distance in the solid phase strongly depends on the crystal field effect and on the dipole dipole interactions. 8,9 This is confirmed by, e.g., the existence of three different modifications of 1 phenyl silatrane with transannular distances, Si←N, of 2.132(4), 2.156(4), and 2.193(5) Å. 10-12 Different Ge←N distances were also reported for 1 fluorogermatrane in two inde pendent studies, namely, 2.011(9) Å (see Ref. 13) and 2.104(2) Å (see Ref. 14).Gas phase electron diffraction (GED) data are also of considerable interest for assessing the effects of axial and equatorial substituents on the strength of transannular interaction in metall...

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Experimental and Theoretical Study of the Transannular Intramolecular Interaction and Cage Effect in the Atrane Framework of Boratrane and 1-Methylsilatrane

Cited by 86 publications

References 33 publications

Synthesis and reactivity of novel 3-isothiocyanatopropylsilatrane derived from aminopropylsilatrane: X-ray crystal structure and theoretical studies

Synthesis and reactivity of novel 3-isothiocyanatopropylsilatrane derived from aminopropylsilatrane: X-ray crystal structure and theoretical studies

Chemical bonding in the crystal structure of 1-hydrosilatrane

The molecular and electronic structure features of silatranes, germatranes, and their carbon analogs

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