Substitution reactions Flashcards
What is a ligand?
A ligand is a molecule or ion that forms a coordinate bond with a transition metal by donating a pair of electrons
What are the three different types of ligands?
They can be monodentate, bidentate, and multidentate.
Name some monodentate ligands:
H20, NH3, and Cl-.
Name two bidentate ligands:
Ethane-1,2-diamine (H2NCH2CH2NH2) and Ethanedioate(C2O4 2–)
Name a multidentate ligand:
EDTA+ can form 6 coordinate bonds with the central metal ion. Haem is also and Fe(II) complex with a multidentate ligand.
Does the exchange of the ligands NH3 and H2O cause a change in coordination number and why?
No, it does not because they are both similar in size(small) and are uncharged.
How is oxygen transported in the blood and why is CO toxic?
Oxygen forms a co-ordinate bond to Fe(II) in haemoglobin, enabling oxygen to be transported in the blood. Carbon monoxide is toxic because it replaces oxygen by coordinately bonding to Fe(II) in haemoglobin as they are better ligands.
What shape does a complex with a coordination number of 4 make?
They can form a tetrahedral shape or square planar shape (only cis-platin).
What type of isomerism takes place in octahedral and square planar complexed where there are two ligands of one type different from the other ligands?
Cis-trans isomerism. Cis(next to each other) trans(opposite each other) is a special type of EZ isomerism.
In what conditions does optical isomerism take place in complexes?
In an octahedral complex with three bidentate ligands.
What is the chelate effect?
When bidentate and multidentate ligands replace monodentate ligands from complexes as they have more coordinate bonds. The resulting complex is more stable as it has increased entropy (because of more molecules in the product side).
