Tellurium-tetrachloride-tetramer-from-xtal-2000-3D-balls

A cubane-type cluster is an arrangement of atoms in a molecular structure that forms a

cube In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. Viewed from a corner it is a hexagon and its net is usually depicted as a cross. The cube is the on ...

. In the idealized case, the eight vertices are symmetry equivalent and the species has O_h symmetry. Such a structure is illustrated by the

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

cubane. With

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

, cubane has carbon atoms at the corners of a cube and covalent bonds forming the edges. Most cubanes have more complicated structures, usually with nonequivalent vertices. They may be simple covalent compounds or macromolecular or supramolecular cluster compounds.

Examples

Other compounds having different elements in the corners, various atoms or groups bonded to the corners are all part of this class of structures. Inorganic cubane-type clusters include selenium tetrachloride, tellurium tetrachloride, and

sodium silox Sodium silox is the name for an organosilicon compound that serves as a source of the siloxide anion CH3)3Csub>3SiO−. Complexes of this bulky anionic ligand often adopt with low coordination numbers. Examples include Ti(silox)3, Nb(silox)3(PMe ...

. Cubane clusters are common throughout bioinorganic chemistry. Ferredoxins containing e₄S₄ iron–sulfur clusters are pervasive in nature. The four iron atoms and four sulfur atoms form an alternating arrangement at the corners. The whole cluster is typically anchored by coordination of the iron atoms, usually with

cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, s ...

residues. In this way, each Fe center achieves tetrahedral coordination geometry. Some e₄S₄clusters arise via dimerization of square-shaped e₂S₂precursors. Many synthetic analogues are known including heterometallic derivatives. DasCubane.png,

Das cubane In coordination chemistry, the Das cubane is a transition metal carboxylate complex with the formula

oO(OAc)py OO or oo may refer to: Science and technology * ʻŌʻō, an extinct bird of the genus ''Moho'' * Object-oriented programming, a computer programming paradigm * O.O (also O.o or o.O), an emoticon to represent two eyes and a nose or mouth Tran ...

where OAc is acetate and py is pyridine. The compound is named after Birinchi K. Das, who led the team that discovered the cluster. ...

sub>4 (OAc =

acetate An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called ...

; py =

pyridine Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakl ...

) Fe4S4.svg, Ferredoxin (4Fe-4S-cubane) Oxygen Evolving Complex Crystal structure to 1.9 Angstrom Resolution.png, CaMn₃O₄ cubane in

Photosystem II Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants, algae, and cyanobacteria. Within the photos ...

. Cubane-3D-balls.png, Cubane, C₈H₈ Several alkyllithium compounds exist as clusters in solution, typically

tetramer A tetramer () (''tetra-'', "four" + '' -mer'', "parts") is an oligomer formed from four monomers or subunits. The associated property is called ''tetramery''. An example from inorganic chemistry is titanium methoxide with the empirical formula T ...

s, with the formula Lisub>4. Examples include methyllithium and ''tert''-butyllithium. The individual RLi molecules are not observed. The four lithium atoms and the carbon from each alkyl group bonded to them occupy alternating vertices of the cube, with the additional atoms of the alkyl groups projecting off their respective corners. Octaazacubane is a hypothetical

allotrope Allotropy or allotropism () is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element: the ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...

with formula N₈; the nitrogen atoms are the corners of the cube. Like the carbon-based cubane compounds, octaazacubane is predicted to be highly unstable due to angle strain at the corners, and it also does not enjoy the kinetic stability seen for its organic analogues.

References

{{Reflist Molecular geometry