The crystal structure of octamethylspiro [5.5] pentasiloxane: rotation about the ionic silicon–oxygen bond

Roth, W. L.; Harker, David

doi:10.1107/s0365110x48000077

Cited by 46 publications

(5 citation statements)

References 2 publications

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“…This result is particularly significant since Voronkov11 has suggested from examination of tetrahedral models that 2,2',2"-nitrilotriethoxysilanes can take on a nonstrained "biconvex" structure that excludes any Si-N interaction, as well as the slightly strained "concavo-convex" configuration confirmed in this study. Our bond length is nevertheless somewhat longer than the values (1.94-2.09 A) recently reported12 for pentacoordinate Si-N bonds in dimethylsilylamine pentamer, and substantially longer than the range21-23 of about 1.7-1.8 A reported for Si-N 1.508 (24) bonds to tetrahedral silicon. Taken together with the measurable distortion of the structure from an ideal trigonal bipyramid, this result suggests that the Si atom is not fully hybridized as sp3d.…”

Section: Discussioncontrasting

confidence: 62%

Structural studies of pentacoordinate silicon. I. Phenyl-(2,2',2''-nitrilotriethoxy)silane

Turley¹,

Boer²

1968

J. Am. Chem. Soc.

121

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The crystal structure of (CeH5)Si(OCH2CH2)3N has been determined by three-dimensional X-ray diffraction methods and confirms the predicted pentacoordination of silicon in this compound. The distorted trigonal bipyramid coordination geometry of the silicon has the three equatorial oxygens bent away from the phenyl group toward the nitrogen as shown by the average C-Si-O angle of 97.1 °and the average O-Si-O angle of 118.5°. Bond distances to the silicon are Si-O(l) 1.638 Á, Si-0(2) 1.664 Á, Si-0(3) 1.665 A, Si-C 1.882 Á, and Si-N 2.193 A. The space group is Pbca with a = 13.220 A, b = 18.524 Á, c = 10.050 A and eight molecules per unit cell. The structure was solved by iterative application of Sayre's method in three dimensions using a visual data set. Refinement was by full matrix least squares to a final reliability index of 10.8%. Data Collection. Crystals of phenyl-(2,2',2"-nitrilotriethoxy)silane are colorless with a lath-like habit and a melting point of 207-(12) R.

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Section: Discussioncontrasting

confidence: 62%

Structural studies of pentacoordinate silicon. I. Phenyl-(2,2',2''-nitrilotriethoxy)silane

Turley¹,

Boer²

1968

J. Am. Chem. Soc.

121

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“…The differences in non-equivalent Si-O distances, Si-C distances and Si-O-Si bond angle would probably not be significant, the mean values being 1.63A, agree well with those reported by other investigators. [1][2][3][4][5][6] The mean Si-C distance agrees with those found for II and spirosiloxane.…”

Section: Structure Determinationsupporting

confidence: 76%

The Crystal and Molecular Structure of the Dehydrated Tetramer of 1,2-Dimethyldisilanetetraol, (CH3)8Si8O8

Higuchi¹,

Shimada²

1966

Bulletin of the Chemical Society of Japan

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The crystal and molecular structure of (CH3)8Si8O8 has been determined by means of the Patterson projections and refined by the two-dimensional Fourier technique and the least-squares method. The space group is P4/nnc, with four molecules per unit cell. The unit cell constants are a=11.73±0.02 Å, and c=17.17±0.02 Å. The skeleton of a molecule consists of two “crown-shaped” (–Si–O–)4 rings which are crystallographically independent of each other and are connected by four Si–Si bonds along the c axis. The four six-membered (–Si–Si–O–)2 rings thus formed have boat forms. Hence, a molecule forms a cage-like conformation with an approximate symmetry of 4/mmm. Each molecule in the unit cell is surrounded by four adjacent molecules related with centers of symmetry; these molecules form, in a sense, a layer perpendicular to the c axis.

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“…Compound 4 displays an extremely unusual core with two perpendicular flat sixmembered siloxane rings. This disposition had only been reported previously in the octamethyl spiro-5,5-pentasiloxane published by Roth et al (CSD code OMSSIO, [42]). Siloxane core structures with a spiral disposition of two cyclic units can also be found in the structures with CSD codes MIWKIP [43] and TMPSIX [44], although in those cases the siloxane rings are not planar.…”

Section: Single Crystal X-ray Diffractionsupporting

confidence: 70%

Unexpected Formation of a Silicon-Centered Spirocyclic Oligosiloxane Bearing Eight Pendant Ferrocene Units

2022

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An intriguing but rare silicon-centered spirocyclic compound, spiro[5.5]octaferrocenylpentasiloxane (4) featuring silicon fused six-membered ferrocenyl-functionalized siloxane rings, has been obtained during the thermally induced transformation of triferrocenylsilane Fc3Si–H (1) into triferrocenylsilanol Fc3Si–OH (2), when N,N-dimethylformamide (DMF) was used as a solvent in the presence of the metal carbonyl Mo(CO)6. The unexpected formation of the maximally ferrocenyl substituted silicon centered spirocyclic 4 involves the obtention, and subsequent condensation, of different ferrocenylsilanol intermediates. Spirocyclic silicate 4 has been characterized using a combination of MALDI-TOF mass spectrometry, elemental analysis, and single crystal X-ray diffraction analysis.

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The crystal structure of octamethylspiro [5.5] pentasiloxane: rotation about the ionic silicon–oxygen bond

Cited by 46 publications

References 2 publications

Structural studies of pentacoordinate silicon. I. Phenyl-(2,2',2''-nitrilotriethoxy)silane

Structural studies of pentacoordinate silicon. I. Phenyl-(2,2',2''-nitrilotriethoxy)silane

The Crystal and Molecular Structure of the Dehydrated Tetramer of 1,2-Dimethyldisilanetetraol, (CH3)8Si8O8

Unexpected Formation of a Silicon-Centered Spirocyclic Oligosiloxane Bearing Eight Pendant Ferrocene Units

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