EVISA Contact EVISA | Sitemap | Home   
 Advanced search
The establishment of EVISA is funded by the EU through the Fifth Framework Programme (G7RT- CT- 2002- 05112).

Supporters of EVISA includes:



A coordination entity is composed of a central atom, usually that of a metal, to which is attached a surrounding array of other atoms or group of atoms, each of which is called a ligand. A coordination entity may be a neutral molecule, a cation or an anion. The ligands may be viewed as neutral or ionic entities that are bonded to an appropriately charged central atom. It is standard practice to think of the ligand atoms that are directly attached to the central atom as defining a coordination polyhedron (tetrahedron, square plane, octahedron, etc.) about the central atom. The coordination number is defined as being equal to the number of sigma-bonds between ligands and the central atom; this definition is not necessarily appropriate in all areas of (coordination) chemistry. In a coordination formula, the central atom is listed first. The formally anionic ligands appear next and they are listed in alphabetic order according to the first symbols of their formula. The neutral ligands follow, also in alphabetical order, according to the same principle. The formula for the entire coordination entity, whether charged or not, is enclosed in square brackets. In a coordination name, the ligands are listed in alphabetical order, without regard to charge, before the name of the central atom. Numerical prefixes indicating the number of ligands are not considered in determining that order. All anionic coordination entities take the ending -ate, whereas no distinguishing termination is used for cationic or neutral coordination entities.

The term "coordination" was found in the following pages:


Imprint     Disclaimer

© 2003 - 2010 by European Virtual Institute for Speciation Analysis ( EVISA )