coordination chemistry Flashcards
(25 cards)
What is a complex
positively charged central ion ( an acceptor ) surrounded in a symmetrical manner by ions or ligands
How are ligands held to the metal
Dative bonds
What is a monodentate ligand
One donor atom - can be neutral or anionic ligands
What is an ambidentate ligand
A molecule that can bind through two atoms but not at once, e.g. nitro and nitrito, or SCN.
What is chelation ?
The formation of complexes by chelate ligands- simultaneous binding of multiple donor atoms by forming rings around the central atom
What is a bridging ligand, and give an example
a ligand attached to two or more central atoms, eg Cl- atoms connected to Pt
Whats coordination number
number of ligand atoms directly bonded to central metal in the complex
What does the coordination number depend on
Size of central atom/ion
Steric interaction of ligand
Electronic interactions
What are isomers
2 or more different compounds having the same formula but different structures
What are conformational isomers
interconvertible by bond rotation unlike configurational isomers
What are the two types of stereoisomers
Geometric and optical
What are the types of structural isomerism
Coordination, hydrate, ionisation, linkage and ligand
What are optical isomers
Not superimposable on their mirror image, same atoms and bonds but the bonds differ in their orientation
What are coordination isomers
Possible for compounds made from cationic and anionic complex ions possible to vary the ions. NEUTRAL species ARE NOT allowed.
What are hydrate isomers
Possible with water in or out of the coordination sphere
What are ionisation isomers
Compounds with a complex ion and counter-ion. Isomers produce different ions in solution. Isomers differ in the distribution of ions between directly coordinated and counter-ions.
What kind of ligands are required for linkage isomerism
Ambidentate ligands
When does ligand isomerism happen
Confined to organic liquids
How do you write the formula for complex ions
in [], cation and then anion. Metal ion first. Anionic ligands next and then neutral ligands in alphabetical order.
How do you name the complex
Cation named first and then the anion, ligands listed alphabetically before the metal. e.g. pentaaminechlorocobalt(III)chloride - [CoCl(NH3)5]Cl
What is the overall stability constant
The equilibrium constant for the overall reaction. Takes each water displacement into account.
How do you work out the overall stability constant
M + nL -> MLn
[MLn]/[M][L]^n
What do large values of B (beta ) mean
The conc of the complex is larger than the conc of its constituents.
What makes a complex stable
logB >0 , delta G is negative
