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Tetrahedrons

Be40(02CCH3)e. The acetate is typical of the basic beryllium carboxylates (Be(OH)2 plus ethanoic acid). The structures have O at the centre of a tetrahedron of Be with carb-oxylate spanning each edge of the tetrahedron. Be(02CCH3)2 is formed from BeCl2 and glacial ethanoic acid. [Pg.58]

The point groups T, and /j. consist of all rotation, reflection and rotation-reflection synnnetry operations of a regular tetrahedron, cube and icosahedron, respectively. [Pg.147]

Figure Bl.8.4. Two of the crystal structures first solved by W L Bragg. On the left is the stnicture of zincblende, ZnS. Each sulphur atom (large grey spheres) is surrounded by four zinc atoms (small black spheres) at the vertices of a regular tetrahedron, and each zinc atom is surrounded by four sulphur atoms. On the right is tire stnicture of sodium chloride. Each chlorine atom (grey spheres) is sunounded by six sodium atoms (black spheres) at the vertices of a regular octahedron, and each sodium atom is sunounded by six chlorine atoms. Figure Bl.8.4. Two of the crystal structures first solved by W L Bragg. On the left is the stnicture of zincblende, ZnS. Each sulphur atom (large grey spheres) is surrounded by four zinc atoms (small black spheres) at the vertices of a regular tetrahedron, and each zinc atom is surrounded by four sulphur atoms. On the right is tire stnicture of sodium chloride. Each chlorine atom (grey spheres) is sunounded by six sodium atoms (black spheres) at the vertices of a regular octahedron, and each sodium atom is sunounded by six chlorine atoms.
Roth H D, Weng H and Herbertz T 1997 CIDNP study and ab initio calculations of rigid vinylcyclopropane systems evidence for delocalized ring-closed radical cations Tetrahedron 53 10 051-70... [Pg.1618]

Nierengarten J-F, Schall C, Nicoud J-F, Fleinrich B and Guillen D 1998 Amphiphilic cyclic fullerene bisadducts synthesis and Langmuir films at the air-water interface Tetrahedron Lett. 39 5747-50... [Pg.2431]

Mirkin C A and Caldwell W B 1996 Thin film, fullerene-based materials Tetrahedron 52 5113-30... [Pg.2431]

Figure C2.12.1. Origin of ion exchange capacity in zeolites. Since every oxygen atom contributes one negative charge to the tetrahedron incoriDorated in the framework, the silicon tetrahedron carries no net charge while the aluminium tetrahedron carries a net charge of-1 which is compensated by cations M. Figure C2.12.1. Origin of ion exchange capacity in zeolites. Since every oxygen atom contributes one negative charge to the tetrahedron incoriDorated in the framework, the silicon tetrahedron carries no net charge while the aluminium tetrahedron carries a net charge of-1 which is compensated by cations M.
Figure 4. The H3 and H4 loops. Ac the center, the conical intersections are shown schematically an equilateral triangle for H3 and a perfect tetrahedron for Kt, <2p> Jid Q, are the phase-preserving and phase-inverting coordinates, respectively. Figure 4. The H3 and H4 loops. Ac the center, the conical intersections are shown schematically an equilateral triangle for H3 and a perfect tetrahedron for Kt, <2p> Jid Q, are the phase-preserving and phase-inverting coordinates, respectively.
The H4 system is the prototype for many four-elecbon reactions [34]. The basic tetrahedral sfructure of the conical intersection is preserved in all four-electron systems. It arises from the fact that the four electrons are contributed by four different atoms. Obviously, the tefrahedron is in general not a perfect one. This result was found computationally for many systems (see, e.g., [37]). Robb and co-workers [38] showed that the structure shown (a tetraradicaloid conical intersection) was found for many different photochemical transformations. Having the form of a tetrahedron, the conical intersection can exist in two enantiomeric structures. However, this feature is important only when chiral reactions are discussed. [Pg.340]

The two coordinates defined for H4 apply also for the H3 system, and the conical intersection in both is the most symmetric structure possible by the combination of the three equivalent structures An equilateral triangle for H3 and a perfect tetrahedron for H4. These sbnctures lie on the ground-state potential surface, at the point connecting it with the excited state. This result is generalized in the Section. IV. [Pg.340]

Methane, CH4, for example, has a central carbon atom bonded to four hydrogen atoms and the shape is a regular tetrahedron with a H—C—H bond angle of 109°28, exactly that calculated. Electrons in a lone pair , a pair of electrons not used in bonding, occupy a larger fraction of space adjacent to their parent atom since they are under the influence of one nucleus, unlike bonding pairs of electrons which are under the influence of two nuclei. Thus, whenever a lone pair is present some distortion of the essential shape occurs. [Pg.38]

When the ammonium ion NH is formed the lone pair becomes a bonding pair and the shape becomes a regular tetrahedron. [Pg.38]

Addition of halide ions to aqueous copper(II) solutions can give a variety of halo-complexes for example [CuCl4] (yellow square-planar, but in crystals with large cations becomes a flattened tetrahedron) [CuClj] (red, units linked together in crystals to give tetrahedral or distorted octahedral coordination around each copper). [Pg.413]

Description by rotational lists was introduced by Cook and Rohde [110] in the specification of the Standard Molecular Data (SMD) format [111]. In this stereochemical approach, the basic geometrical arrangements around a stcrcoccntcr arc defined in a list (c.g., square, tetrahedron, etc.). The atoms in those stcrcoclcmcnts are also labeled with numbers in a pre-defined way (Figure 2-72),... [Pg.80]

It is often difficult to represent inorganic compounds with the usual structure models because these structures are based on complex crystals space groups), aggregates, or metal lattices. Therefore, these compounds are represented by individual polyhedral coordination of the ligands such as the octahedron or tetrahedron Figure 2-124d). [Pg.135]


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Anionic tetrahedron complex

Archimedean solids truncated tetrahedron

Base tetrahedra

Bicapped tetrahedron

Bicapped tetrahedron distortion

Bonding tetrahedron

Carbon tetrahedron

Chain, tetrahedron

Chemical Bond Tetrahedron Geometry

Chiral Tetrahedra

Compatibility tetrahedrons

Compounds Based on Edge-sharing Dimers of Tetrahedra

Concentration tetrahedron

Coordination polyhedra tetrahedron

Cu tetrahedra

Edge tetrahedra

Ethanes tetrahedra

Extended tetrahedron

Face tetrahedra

Finite clusters of tetrahedra

Fire tetrahedron

Fire tetrahedron components

Frank—Kasper tetrahedron

Global equilibrium conditions for hybridization tetrahedra

Hybrid orbitals hybridization tetrahedron

Hybridization tetrahedron

Hydrogen bonding, between tetrahedra

Interspace of tetrahedron

Inverted tetrahedra

Iron tetrahedron

Isolated tetrahedra

LL, tetrahedron

Librations of hybridization tetrahedra

Linking silicon-oxygen tetrahedra

Local equilibrium conditions for hybridization tetrahedra and quasitorques

M4 tetrahedra

Material-type tetrahedron

Mesh and Tetrahedra

Metallo-tetrahedron

Mixed bonding tetrahedron

Molecular tetrahedron

Monocapped trigonal bipyramid tetrahedron

Morphology tetrahedrons

Ni4 tetrahedra

Nickel tetrahedra] complexes

Number 4 Tetrahedron

Orientation Specificity of the Tetrahedron

Orientation tetrahedron

PO4 tetrahedron

Particles tetrahedron

Particles truncated tetrahedron

Pentagonal dodecahedron or capped tetrahedron - the controversy

Phosphate tetrahedra

Platonic tetrahedron

Psi tetrahedron

Quaternion form of the hybrid orbitals and hybridization tetrahedra

Regular tetrahedron

Sb4 tetrahedra

SiN4 tetrahedra

SiO tetrahedra

Silica tetrahedra

Silicate minerals tetrahedra

Silicate tetrahedra

Silicon tetrahedron

Single tetrahedron

Structures built from tetrahedra and octahedra

Structures with finite clusters of tetrahedra and octahedra

Symmetry tetrahedron

TO4 tetrahedra

Taste tetrahedron

Tetrahedra Subject

Tetrahedra capping

Tetrahedra clusters

Tetrahedra edge-sharing

Tetrahedra face-sharing

Tetrahedra linkage

Tetrahedra rings

Tetrahedra sharing edges only

Tetrahedra sharing vertices only

Tetrahedra vertex-sharing

Tetrahedra, distorted

Tetrahedral group Tetrahedron

Tetrahedron A polyhedron with

Tetrahedron Theory

Tetrahedron and the Related Cube

Tetrahedron angular coordinates

Tetrahedron bond length

Tetrahedron building blocks

Tetrahedron complex

Tetrahedron complex Chain

Tetrahedron complex Framework

Tetrahedron complex Layer

Tetrahedron complex Linear

Tetrahedron connectivity

Tetrahedron cube and

Tetrahedron fire theory

Tetrahedron geometry

Tetrahedron method

Tetrahedron model

Tetrahedron notations

Tetrahedron of Fire

Tetrahedron shape

Tetrahedron spacing

Tetrahedron stacking

Tetrahedron structure

Tetrahedron symmetry groups

Tetrahedron, Cubo-Octahedronal and Octahedron

Tetrahedron, crystal field splitting

Tetrahedron, views

Tetrahedron, volume

Tetrahedron. See

The Tetrahedron Method

The tetracapped tetrahedron of metal atoms

Thompson tetrahedron

Tire tetrahedron

Transformed tetrahedron

Tricapped tetrahedron structures

Truncated tetrahedron

VO4 tetrahedra

Vertex tetrahedra

Vertex-sharing Tetrahedra. Silicates

Yoder-Tilley basalt tetrahedron

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