Ligand substitution Flashcards
What is ligand substitution?
This is when one ligand in a complex ion is replaced by another ligand
What are the two ligand subsitiutions for [Cu(H20)6]2+
- to [Cucl4] 2-
- to [cu(NH3)4(H20)2]2+
How do you form [Cu(H20)6]2+
dissolve cuso4 in water
How does [Cucl4] 2- form?
- 6 water ligands have been substituted for 4 chloride ligands
- the colour change is pale blue to yellow
- [Cu(H20)]2+ + 4Cl- = [Cucl4]2- + 6H20
How does [cu(NH3)4(H20)2]2+ form?
- excess ammonia is added to [Cu(H20)6]2+ which forms [cu(NH3)4(H20)2]2+
- 4 ammonia ligands have replaced 4 water ligands
Overall reaction = [Cu(H20)6]2+ + 4NH3 = [Cu(NH3)4(H20)2]2+ + 4H20
2 step reaction =
1. [Cu(H20)6]2+ + 2NH3 = [Cu(H20)4(OH)2] + 2NH4 +
pale blue pale blue precipitate
- [Cu(H20)4(OH)2] + 2NH3 + 2NH4+ = Cu(NH3)4(H20)2]2+ + 4H20
dark blue solution
What ligand substitution occurs for cr3+?
- excess ammonia is added to [Cr(H20)6]3+ which is formed from dissolving kcr(so4)2 in water, forming [Cr(H20)6]3+
overall equation =
[Cr(H20)6]3+ + 6NH3 = [Cr(NH3)6]3+ + 6H20
dark green purple
2 step reaction =
1. first Cr(OH)3 forms when ammonia is added dropwise
2. It then dissolves in excess ammonia
What is the equation for haemoglobin?
Hb-Co2 + O2 = Hb - O2 + Co2
Describe the reactions of Fe2+ in haemoglobin?
- haemoglobin contains 4 protein chains. Each protein chain has a haem group containing Fe2+ which can bind to oxygen
Near the lungs
- Higher concentration of 02 and low Co2
- equillibrium shifts to the right
- Hb-Co2 + O2 = Hb - O2 + Co2
- oxygen binds to haemoglobin and forms oxyhaemoglobin
Away from the lungs
- Higher concentration of C02 and low concentration of 02
- equillibrium shifts to the left
- Co2 attaches to haemoglobin and 02 is released
Describe the bind of CO?
- CO can bind to Fe2+ in haemoglobin and form carboxyhaemoglobin
- CO has a stronger affinity and has an irreversible bind to haemoglobin preventing oxygen from being transported
