New sterically hindered bis(3-tert-butyl-2-hydroxy-5-methylbenzyl)amine was synthesized based on 2-tert-butyl-4-methylphenol. The reaction of the latter with N, N-dimethylformamide affords N, N-bis(3-tert-butyl-2-hydroxy-5-methylbenzyl)formamide. According to the X-ray diffraction data, this reaction product occurs in the crystal as a dimer stabilized by a bifurcated hydrogen bond. The intermolecular component of the C=O⋯H-O hydrogen bond (l = 1.990 Å) between the carbonyl oxygen atom of one molecule and the phenolic hydroxy group of another molecule ensures the formation of dimers. Another component is the intramolecular C=O⋯H-O hydrogen bond (l = 1.754 Å) between the carbonyl oxygen atom and the phenolic hydroxy group of the same molecule. In the crystal, the dimers are linked via C-H…π interactions to form long chains (2.741 Å).

By X-ray diffraction the crystal and molecular structure of N-(1-silatranylmethyl)phthalimide (SMP) is determined. The coordination polyhedron of the silicon atom in SMP, as in all silatranes, is a trigonal bipyramide; the phthalimide cycle is planar. The data presented indicate that the silatranylmethyl group almost does not affect the geometry of the phthalimide moiety.

Zinc di-(4-chlorphenylthioacetate) dihydrate (4-ClC6H4SCH2COO)2Zn·2H2O (ZTD) is obtained in the reaction of protatrane 4-chlorphenylthioacetate 4-ClC6H4SCH2COO s- 2 ·N+H(CH2CH2OH)3 with zinc dichloride (ZnCl2) in aqueous alcohol. X-ray diffraction is used to study the crystal structure of ZTD and compare it with related compounds. All intermolecular O…O contacts of the neighboring zinc polyhedra are short in ZTD molecules. Apparently, the short intermolecular O…O contacts cause distortions of the octahedral environment of the zinc atom.

The crystal structures of anhydrous 1-germatranol and its complex with HCCl3 are centrosymmetrical dimers because of their intermolecular hydrogen bonds. In the germatranol crystal, the axial and equatorial oxygen atoms of its two molecules are hydrogen bonded into an eight-membered coordination cycle. In the complex with HCCl3, the two molecules of germatranol are likewise linked in dimers, and both axial oxygen atoms are H bonded with HCCl3. In the investigated structures, the axial Ge—O bond is shorter than the equatorial ones. Depending on the number and strength of the hydrogen bonds, the interatomic Ge—O and Ge ← N distances change markedly. The quantitative estimates of the H bond energy are obtained from quantum chemical calculations of the model systems containing 1-germatranol and HCCl3 molecules.

According to the data of X-ray diffraction analysis and quantum chemical calculations, in the hypervalent silicon compounds where the coordination cycle is closed by the C=O→Si-F fragment, the O→Si interatomic distance is governed by the orientation of the silicon atom determined by the C=O→Si angle. This is an indication of a directivity of the coordination bond O→Si; a regular variation in the nature of the latter is reflected in the observed dependence of the O→Si distance on the C=O→Si angle.

The molecular structure of 1-methyl-1-fluoroquasisilatrane (2-methyl-2-fluoro-1,3-dioxa-6-aza-2-silacyclooctane) MeFSi(OCH 2 CH 2 ) 2 NH ( I ) is determined by single crystal X-ray diffraction at 100 K. The coordination polyhedron of the silicon atom in this molecule is a slightly distorted trigonal bipyramid with an NH group and a strongly electron-withdrawing fluorine atom in the axial positions, and two endocyclic oxygen atoms and a CH 3 group in three vertices of the equatorial plane. The axial angle N→SiF is 171°. The length of the transannular donor-acceptor bond N→Si (2.058 Å) is as small as in 1-fluorosilatrane. The axial bond F-Si (1.660 Å) is longer than that in 1-fluorosilatrane and tetrahedral silicon compounds.

1-(2-Pyridyloxy)silatrane was synthesized by trans-etherification of 1-ethoxysilatrane with 2-hydroxypyridine as well as by the reaction of the latter with tetraethoxysilane and triethanolamine. Its structure was established by the XRD analysis of a single crystal, and in solution using the methods of (1)H, (13)C, (29)Si NMR and IR spectroscopy.

The crystal and molecular structure of 1-phenyl-1-fluoro-5-methylquasisilatrane PhFSi(OCH 2 CH 2 ) 2 NMe was investigated by X-ray diffraction at 100 K. The coordination polyhedron of the silicon atom in the molecule is a slightly distorted trigonal bipyramid containing fluorine and nitrogen atoms in the axial positions and two endocyclic oxygen atoms and the carbon atom of the phenyl group at three vertices of the equatorial plane.

The crystal and molecular structure of N-(trifluorosilylmethyl)glutarimide has been determined by X-ray diffraction. The independent part of the unit cell of the single crystal contains two molecules that differ in the conformation of the glutarimide heterocycle. The coordination polyhedron of the silicon atom in them is a trigonal bipyramid. The bond lengths and angles in these molecules are compared with those in the crystal structures of related compounds.

The synthesis of pentacoordinate organosilicon compounds, N-(trifluorosilylmethyl)succinimide (1) and N-(trifluorosilylmethyl)glutarimide (2) is described. The X-ray crystal analysis of compound 1 shoves a slightly distorted trigonal-bipyramidal coordination at silicon. Dynamic F-19, C-13, and Si-29 NMR studies confirm the existence of an O -> Si intramolecular hypervalent bond in solution. (c) 2006 Wiley Periodicals, Inc.

The crystal and molecular structure of 1-(trimethylsilylmethyl)benzotriazole has been established by X-ray diffraction (XRD) analysis. The coordination polyhedron of the silicon atom in this molecule is a tetrahedron. The bond lengths and angles of the 1-(trimethylsilylmethyl)benzotriazole molecule were compared with those of related crystal structures.

Only 2-benzotriazolyl sodium is formed in the reaction of benzotriazole (BtH) with sodium methoxide. Its reaction with trimethyl- or trimethoxy-(chloromethyl)-silane affords a mixture of 1- and 2-(trimethylsilylmethyl)-1 and 2, and 1- and 2-(trimethoxysilylmethyl) benzotriazoles, 3 and 4, which were separated into the individual isomers. trans-Etherification of the latter with tris-(2-hydroxyethyl) amine leads to 1- and 2-(silatranylmethyl) benzotriazoles 5 and 6. The electronic structures of the compounds prepared were investigated using IR, UV, multinuclear NMR spectroscopy, mass spectrometry, and X-ray diffraction. The organosilicon benzotriazole derivatives 1, 3 and 5 show a benzenoid structure, whereas 2, 4 and 6 have ortho-quinonoid structures.