Pentacoordinate silicon.  Crystal structure of dimethylsilylamine pentamer

Rudman, Reuben; Hamilton, Walter C.; Novick, Stewart E.; Goldfarb, Theodore D.

doi:10.1021/ja00996a014

Cited by 43 publications

(13 citation statements)

References 2 publications

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“…Computer programs SHELX76 (Sheldrick, 1976), XANADU (Roberts & Sheldrick, 1976), XRA Y76 (Stewart, Machin, Dickinson, Ammon, Heck & Flack, 1976) and OR TEPII (Johnson, 1976). Table 1 lists derived fractional coordinates.$ The coordinates of the nonhydrogen atoms are in close agreement with those previously found (Rudman, Hamilton, Novick & Goldfarb, 1967). Fig.…”

supporting

confidence: 84%

Structure of the dimethylsilylamine pentamer, (C2H9NSi)5. A redetermination

Blake¹,

Ebsworth²,

Welch³

1984

Acta Crystallogr C

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Abstract. Mr=375.8, P2Jm, a=6.408(8), b= 19.491 (6), c=9.467 (3)A, fl=90.79 (7) ° , U= 1182 (3) /~a, Z=2, Dx=l.056Mgm -a, MoKa radiation, ~, = 0.71069/~,,/~ = 0.298 mm -~, T= 118 K, F(000) = 420, R = 0.0504 for 2698 reflections. The unit cell contains two pentameric, ten-membered rings of alternating N and Si atoms. Each ring lies across a crystallographic mirror plane. All Si-N distances [mean 1.976 (4)/~] are equivalent and greater by ca 0.26/~, than that found for the uoassociated molecule in the gas phase. The coordination at N and Si is pyramidal and trigonal bipyramidal respectively. The crystal structure consists of essentially isolated rings packed parallel to each other.

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supporting

confidence: 84%

Structure of the dimethylsilylamine pentamer, (C2H9NSi)5. A redetermination

Blake¹,

Ebsworth²,

Welch³

1984

Acta Crystallogr C

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Section: The Structures Of Disiloxane and Hexamethyldisiloxanementioning

confidence: 71%

“…Rudman, Hamilton, Novick & Goldfarb, 1967;P/lrk/myi, Nagy & Simon, 1975, and references therein), it is somewhat surprising to find a donor-acceptor interaction of this type here since the silyl group is not a good acceptor and the oxygen atom in disiloxane is a poor donor towards such acceptors as trimethylboron. If we equate the O... Si(2) interaction with the incipient SN2 reaction situation, as has been suggested for other crystalline state intermolecular interactions (Biirgi, 1975), then we expect distortions to the intramolecular geometry at Si(2), but not at Si(1).…”

Section: (C) Intermolecular Geometrymentioning

confidence: 86%

The crystal and molecular structures of disiloxane (at 108 K) and hexamethyldisiloxane (at 148 K)

Barrow¹,

Ebsworth²,

Harding³

1979

Acta Crystallogr Sect B

125

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THE STRUCTURES OF DISILOXANE AND HEXAMETHYLDISILOXANE equipment and microdensitometer intensities were obtained from films exposed using Cu Ka radiation. The structures were refined to R = 4-2% over 403 reflexions for disiloxane, and R = 3.5% over 1256 reflexions for hexamethyldisiloxane. Crystalline disiloxane has distorted mm2 molecular symmetry with Si-O = 1.631 (6) A and Si-O-Si = 142.2 (3) °. Crystalline hexamethyldisiloxane has distorted m molecular symmetry with Si-O = 1.626 (5) A and Si-O-Si = 148.8 (2) °. Molecules of disiloxane form infinite chains as a result of weak, but highly directional, intermolecular Si..-O interactions (3.115 A). Hexamethyldisiloxane exists as discrete molecules with no short intermolecular contacts. IntroductionIn water, dimethyl ether, F20 and C120 , the angle at oxygen is close to or less than the tetrahedral value. In silicates and disiloxanes, the angle at oxygen is very much wider. Moreover, it increases from the apparent value of 144.1 ° in disiloxane itself (as measured by electron diffraction in the gas phase) to 180 ° in crystalline hexaphenyldisiloxane. Values for Si-O-Si and Si-O distances in a number of disiloxanes and related compounds are given in Table 7.Most of the features in the vibrational spectra of disiloxane can be interpreted in terms of a model with a linear heavy-atom skeleton (Lord, Robinson & Schumb, 1956). This apparently conflicts with the structure as determined by electron diffraction (Almenningen, Bastiansen, Ewing, Hedberg & Traetteberg, 1963); the two can be reconciled if the molecule is regarded as 'quasi-linear': bent but with a skeletal bending vibration that is low in frequency and large in amplitude. Under these conditions the language of the conventional point-group analysis becomes inappropriate; permutation group theory must be used instead. The appropriate permutation group is isomorphous with D3h , leading to selection rules that are effectively the same as for a molecule with a linear heavy-atom skeleton. A detailed analysis of the weak Raman feature corresponding to the overtone of the skeletal bending mode has led Durig, Flanagan & Kalasinsky (1977) to propose a potential surface with a hump at a linear configuration of height 112 cm -1, and a minimum corresponding to a Si-O-Si angle of 149 °.The concept of quasi-linearity is by now well established, but little is known about the structures of quasilinear molecules in the solid state. The vibrational spectra of disiloxane and hexachlorodisiloxane change on crystallization, implying that there might be associated changes in structure. Disiloxane is a clearly recognized example of quasi-linearity, while it is suggested that features in the Raman spectra of hexamethyldisiloxane imply that this molecule too should be regarded as quasi-linear. We here present the crystal structures of disiloxane and of hexamethyldisiloxane. ExperimentalCrystallographic data ProcedurePure samples of disiloxane and hexamethyldisiloxane were sealed into glass capillaries, which were mounted on Tufnol ins...

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“…The crystal structure was investigated to see, if intermolecular donor-acceptor interactions are present as is the case for Me 2 NSiH 3 [5] and Me 2 NSiH 2 Cl [6], where the Si atoms are pentacoordinated in the solid state.…”

Section: Introductionmentioning

confidence: 99%

“…Data was collected on a Stoe Stadi-4 diffractometer equipped with on Oxford Cryosystems variable temperature decive, graphite-monochromated Cu±Kα radiation, k = 0.154184 nm, T = 150 K. Crystal data for CH 5 ±1 . An absorption correction was applied during refinement using the program Difabs.…”

mentioning

confidence: 99%

Bis(dichlorosilyl)methylamine - Synthesis, Crystal Structure, and Conformational Analysis in the Gas Phase

Fleischer

McKean

Parsons

et al. 1999

Z. anorg. allg. Chem.

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A straightforward preparation has been found for bis(dichlorosilyl)methylamine, (SiHCl2)2NMe (1), involving reaction between H2NMe and an excess of SiHCl3, dissolved either in pentane or THF at 253 K. 1 and a side‐product, 1,3,5‐trichloro‐2,4,6‐trimethylcyclotrisilazane, (–SiHCl–NMe–)3 (2), were identified by elemental analysis, mass spectrometry and 1H‐NMR‐spectroscopy. Some physical, NMR‐ and IR spectroscopical properties of 1 were determined. The molecular and crystal structure of 1 was investigated by single crystal X‐ray diffraction. Selected structural parameters: r(Si–N) 169.7(5), r(Si–Cl) 203.1(2)–204.4(2), r(C–N) 150.0(8) pm; a(SiNSi) 123.6(3), a(SiNC) 118.3(4)/118.0(4)°. Ab initio force field data and infrared intensities were calculated for four conformers of 1. Comparison of the observed and calculated IR spectra favours the two structures found ab initio provided that their actual abundancies are different from those calculated.

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Pentacoordinate silicon. Crystal structure of dimethylsilylamine pentamer

Cited by 43 publications

References 2 publications

Structure of the dimethylsilylamine pentamer, (C2H9NSi)5. A redetermination

Structure of the dimethylsilylamine pentamer, (C2H9NSi)5. A redetermination

The crystal and molecular structures of disiloxane (at 108 K) and hexamethyldisiloxane (at 148 K)

Bis(dichlorosilyl)methylamine - Synthesis, Crystal Structure, and Conformational Analysis in the Gas Phase

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