文档介绍：Chapter 13
Complex Ions and pounds
1. The Relating Conceptions and Definitions
In 1798, . Tassaert obtained yellow crystals of pound having the formula CoCl3·6NH3 from a mixture of CoCl3 and NH3 (aq).
1893, the Werner’s theory was first propose.
Alfred Werner
(1866—1919 )
Certain metal atoms, primarily those of transition metals, have two types of valence or bonding capacity.
One, the primary valence (主价), is based on the number of electrons the atom loses in forming the metal ion.
A secondary valence (副价) is responsible for the bonding of other groups, call ligands, to the central metal ion.
[Co(NH3)6]Cl3
[Co(NH3)6]3+,[)6 ]3-,Ni(CO)4
cation anion neutral
[Co(NH3)6]Cl3,K3[)6],Ni(CO)4
Complex Ions:
pounds
[Co(NH3)6] [)6]
Central atom (ion) — Lewis acid
Ligand — Lewis base
ponent of pounds
Coordination number
ligand
Central ions
monodentate ligand
polydentate ligand
Coordination atom
external world
internal world
Ligands
A ligand is a molecule or ion having the ability to donate electron pairs to central metal atoms or ions.
--- Lewis base
In accepting electron pairs, central metal atoms or ions
--- Lewis acis
Classification
According to the number of donor atoms that bond to the metal:
Monodentate ligands have a single donor atom
Bidentate ligands have two donor atoms
Polydentate ligands include bidentate ligands and others
When the bonding of a polydentate ligand to a metal ion produce a ring (normally with five or six members), we prefer to plex as a chelate. (Ponounced KEY-late). The polydentate ligand is called a chelating agent, and the process of chelate formation is called chelation.
Chelating Agents and pound
oxyhemoglobin
chlorophyll
Coordination atom and Coordination number
Coordination atom is the atom in ligand having a lone pair electron to bond to the central atom.
Coordination number of plex is the number of coordination atoms around the central atom at which bonds to ligands can form.
monodentate
poly