
 E 
  The number of nonbonded electrons at the metal plus the number of electrons in the metalligand bonds should be 18. 
  A molecular polarizability effect occurring by an intramolecular electron displacement (sometimes called the "conjugative mechanism" and, previously, the "tautomeric mechanism") characterized by the substitution of one electron pair for another within the same atomic octet of electrons. 
  If P(x,y,z) dx dy dz is the probability of finding an electron in the volume element dx dy dz at the point of a molecular entity with coordinates x,y,z, then P(x,y,z) is the electron density at this point. 
 www.chem.qmul.ac.uk /iupac/gtpoc/E.html (2409 words) 
