Ueber die geometrischen Isomerien der Hexamethylenderivate

Sachse, H.

doi:10.1002/cber.189002301216

Cited by 140 publications

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“…As there is only one monosubstituted isomer C 6 H 11 Cl, the cyclohexane molecule could be assumed to have D 6h symmetry, with all valency rules satisfied and all hydrogen atoms equivalent (8). On the other hand, the concept of the tetrahedral carbon atom requires a nonplanar carbon ring with bond angles of around 109.5Њ instead of 120Њ, as in a planar hexagon (9). The nonplanar structure (D 3d symmetry) has two kinds of hydrogen atom (called equatorial and axial) and it should therefore give rise to two monosubstituted isomers (Fig.…”

Section: Counting Isomersmentioning

confidence: 99%

Symmetry arguments in chemistry

Dunitz

1996

Proc. Natl. Acad. Sci. U.S.A.

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The use (and misuse) of symmetry arguments in constructing molecular models and in the interpretation of experimental observations bearing on molecular structure (spectroscopy, diffraction, etc.) is discussed. Examples include the development of point groups and space groups for describing the external and internal symmetry of crystals, the derivation of molecular symmetry by counting isomers (the benzene structure), molecular chirality, the connection between macroscopic and molecular chirality, pseudorotation, the symmetry group of nonrigid molecules, and the use of orbital symmetry arguments in discussing aspects of chemical reactivity.

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Section: Counting Isomersmentioning

confidence: 99%

Symmetry arguments in chemistry

Dunitz

1996

Proc. Natl. Acad. Sci. U.S.A.

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“…Cyclohexane derivatives have become, for a long time past, [1] the center of attention of a large number of authors [2][3][4] because, either alone or as part of more complex units, are ubiquous in nature [5] and find numerous applications in chemical and pharmaceutical industries [6]. Moreover, from this type of compounds valuable information on the structural point of view can be taken.…”

Section: Introductionmentioning

confidence: 99%

Molecular structure of mono- and 1,2-aminoderivatives of cyclohexane: Steric strain effects as determining factors

Tomé

Rosado

Ermelinda

et al. 2007

Journal of Molecular Structure: THEOCHEM

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The conformational study of cyclohexylamine and 1,2-cyclohexylamine derivatives was performed. The potential energy surface of every compound was calculated at B3LYP/6-31G(d) and the conformational energy minima were further optimized at B3LYP/augcc-pVDZ level of theory. The geometrical parameters and the electronic energy of each conformer were determined. The internal energy, enthalpy, entropy, Gibbs energy and the relative weight of each conformer in the structure of the respective isomer were calculated at 298.15 K. The steric hindrances in the crowded molecules resulting from the replacement of hydrogens of cyclohexane by amine groups are pointed out by short non-bonded H M H distances and by the consequent bond and dihedral angles distortions relatively to the cyclohexane structure.

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“…This simulation illustrates the great importance of the Xe-N covalent bonding in the stabilization of the XeN 6 nitride. It is worth noting that carbon rings in known cyclohexane molecules adopt similar chair forms where carbon is also in a 4-fold sp 3 hybridization [43]. We probe the formation mechanism of the Xe-N covalent bonds using calculations of the Xe-N distances with increasing pressure (Fig.…”

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confidence: 99%

Stable xenon nitride at high pressures

Peng

Wang

et al. 2015

Phys. Rev. B

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Nitrides in many ways are fascinating since they often appear as superconductors, high energy density and hard materials. Though there exist a large variety of nitrides, noble gas nitrides are long missing in nature. Pursuit of noble gas nitrides has therefore become the subject of topical interests, but remains as a great challenge since molecular nitrogen (N 2 , a major form of nitrogen) and noble gases are both inert systems and do not interact at normal conditions. We show through a swarm structure searching simulation that high pressure can lift the reactivity of both N 2 and xenon (Xe), making chemical reaction of them possible. The resultant nitride has a peculiar stoichiometry of XeN 6 , possessing a high-energy-density of approximately 2.4 kJg -1 , rivaling that of the modern explosives. Chemically, XeN 6 is more intriguing with the appearance of chaired N 6 hexagons and an emergent 12-fold Xe by acceptance of unprecedentedly 12 Xe-N weak covalent bonds. Our work opens up the possibility of achieving Xe nitrides whose formation is long sought as impossible.PACS numbers: 61.66.fn, 71.15.Mb, 81.40.Vw Nitrogen (N) is the most abundant element in the Earth's atmosphere and is one of most important constituents of our universe. In air, N exists in the form of diatomic N 2 molecules and has the strongest-known triple N≡N bond. As a result, N 2 is chemically inert[1] and hardly interacts with other elements or substances under normal conditions. Syntheses of useful nitrides for industrial applications rely on chemical methods [2] via, e.g., temperature-programmed reaction, thermal decomposition, electrochemical synthesis, or with the aid of catalysts (e.g., the synthesis of NH 3 ). [3] Nitrides have a variety of intriguing properties, such as superconductivity[4], high energy density [5], and high hardness [6], as well as extraordinary chemical and thermal stability [7].Noble gases (e.g., Ar, Kr, and Xe) as typical closed-shell systems are inert prototype examples and where the famous octet rule[8] originated. They are critical elements[9] because their abundances constrain the models for giant planet formation and the origin of their atmospheres. Among noble gases, Xe has the largest atomic core and is polarizable to form Xe fluorides[10] (or Xe noble metal hexafluorides [11]) and Xe oxides [12] in certain circumstances at ambient conditions due to its low ionization energy and large relativistic effect.[13] However, other Xe compounds are only synthesizable by using Xe fluoride precursors, instead of Xe gas, in the reaction with other organics or inorganics.Since both N 2 and Xe are inert, they do not directly interact at ambient conditions. Although Xe and N containing compounds have been seen at ambient pressure in (FXe)[N(SO 2 F) 2 ] salts [14], the syntheses of these salts relied on the precursors of the cationic (FXe) + and anionic Ncontaining ligands, while not the uses of N 2 and Xe gases [13]. All of these as-synthesized complex salts have poor thermal stability, and most of them decompose explosi...

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Ueber die geometrischen Isomerien der Hexamethylenderivate

Cited by 140 publications

References 0 publications

Symmetry arguments in chemistry

Symmetry arguments in chemistry

Molecular structure of mono- and 1,2-aminoderivatives of cyclohexane: Steric strain effects as determining factors

Stable xenon nitride at high pressures

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