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What is Homoleptic Complexes?
Grade Level:
Class 12
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Definition
What is it?
Homoleptic complexes are special types of coordination compounds where the central metal atom or ion is bonded to only one type of ligand. Think of it like a team where all players are experts in the same skill, surrounding one captain. All the 'hands' holding the central 'body' are identical.
Simple Example
Quick Example
Imagine you have a cricket team, and all 11 players are specialist batsmen. No bowlers, no wicketkeepers, just batsmen. In this team, the captain (central metal) is surrounded by only one type of player (ligand – batsmen). This is like a homoleptic complex, where all the surrounding 'players' are identical.
Worked Example
Step-by-Step
Let's identify if [Co(NH3)6]3+ is a homoleptic complex.
STEP 1: Identify the central metal atom/ion. Here, it is Cobalt (Co).
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STEP 2: Identify the ligands (the molecules or ions bonded to the central metal). Here, the ligand is Ammonia (NH3).
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STEP 3: Check if there is only one type of ligand present. In this complex, only NH3 ligands are attached to Cobalt.
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STEP 4: Since only one type of ligand (NH3) is bonded to the central metal (Co), it fits the definition.
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ANSWER: Yes, [Co(NH3)6]3+ is a homoleptic complex.
Why It Matters
Understanding homoleptic complexes is crucial in chemistry, especially in designing new materials for technology. These complexes are used in creating catalysts for chemical reactions, developing new sensors in medicine, and even in making advanced materials for electronics. Knowing this helps engineers and scientists build better tools for the future.
Common Mistakes
MISTAKE: Confusing homoleptic with heteroleptic complexes. | CORRECTION: Remember, 'homo' means 'same', so homoleptic means only ONE type of ligand. 'Hetero' means 'different', so heteroleptic means MULTIPLE types of ligands.
MISTAKE: Only looking at the number of ligands, not their type. | CORRECTION: Even if there are many ligands, if they are all of the same chemical type (e.g., all water molecules), it's homoleptic. The number doesn't matter as much as the variety.
MISTAKE: Forgetting that the central atom can be an ion. | CORRECTION: The central 'metal' can be a neutral atom or a positively charged ion. The definition of homoleptic applies to both.
Practice Questions
Try It Yourself
QUESTION: Is [Ni(CO)4] a homoleptic complex? (CO is carbon monoxide) | ANSWER: Yes, because only one type of ligand (CO) is attached to the central metal (Ni).
QUESTION: Identify the central metal and ligand in [Fe(CN)6]4-. Is it a homoleptic complex? | ANSWER: Central metal: Fe (Iron). Ligand: CN- (Cyanide). Yes, it is a homoleptic complex as only one type of ligand (CN-) is present.
QUESTION: A complex has a central metal 'M' and is surrounded by three 'A' ligands and two 'B' ligands. Is this complex homoleptic or heteroleptic? Explain your reasoning. | ANSWER: This complex is heteroleptic. It has two different types of ligands ('A' and 'B') attached to the central metal 'M', which means it does not fit the definition of a homoleptic complex (which requires only one type of ligand).
MCQ
Quick Quiz
Which of the following is an example of a homoleptic complex?
[Cr(NH3)5Cl]2+
[Co(en)3]3+ (en = ethylenediamine)
[Pt(NH3)2Cl2]
[Fe(H2O)4(OH)2]+
The Correct Answer Is:
B
Option B, [Co(en)3]3+, has only one type of ligand (ethylenediamine, 'en') attached to the central cobalt ion, making it homoleptic. All other options have more than one type of ligand.
Real World Connection
In the Real World
Homoleptic complexes are very important in industries. For example, nickel tetracarbonyl, [Ni(CO)4], is a homoleptic complex used in the Mond process to purify nickel metal, which is then used in making stainless steel for utensils and surgical instruments. Also, some homoleptic complexes are studied for their potential in developing new medicines.
Key Vocabulary
Key Terms
LIGAND: A molecule or ion that binds to a central metal atom to form a coordination complex. | CENTRAL METAL ATOM/ION: The atom or ion at the core of a coordination complex to which ligands are bonded. | COORDINATION COMPLEX: A compound consisting of a central metal atom or ion bonded to a surrounding array of molecules or ions (ligands). | HETEROLEPTIC COMPLEX: A coordination complex where the central metal atom is bonded to more than one type of ligand.
What's Next
What to Learn Next
Now that you understand homoleptic complexes, you should explore 'Heteroleptic Complexes'. This will help you compare and contrast different types of coordination compounds and deepen your understanding of how ligands influence their properties.
