Cheat Sheet: Coordination Compounds | Chemistry Class 12 - NEET PDF Download

 Page 1


Coordination Compounds Cheat Sheet (Class
12 CBSE)
1 Introduction to Coordination Compounds
• Definition : Compounds with a centr al metal atom/ion bonded to ligands
via coordinate bo nds.
• Centr al Me tal : Tr ansition metal (d-block) with vacant orbitals.
• Ligand : Molecule/ion donating electron pair (e.g., NH
3
, Cl
–
, H
2
O).
• Coordination Number : Number of ligand atoms attached to the centr al
metal.
• Oxidation State : Charge on metal after accounting for ligand charges (e.g.,
Co
3+
in [Co(NH
3
)
6
]
3+
).
2 Types of Ligands
Type Example Description
Monodentate NH
3
, Cl
–
, CN
–
One donor atom
Bidentate C
2
O
2–
4
, eth ylenediamine (en) Two donor atoms
Polydentate ED T A
4–
Multiple donor atoms
Ambidentate SCN
–
(via S or N) Binds via different atoms
Chelating en, ED T A
4–
F orms ring with metal
3 Nomenclature of Coordination Compounds
• IUP A C Rules :
1. Ligands named first (alphabetical, prefixes: di-, tri-, etc.).
2. Metal named with oxidation state in Roman numer als (e.g., cobalt(III)).
3. Anionic complexes end in “-ate”; neutr al/cationic use metal name.
• Example : [Co(NH
3
)
5
Cl]Cl
2
? Pentaamminechlorocobalt(III) chloride.
1
Page 2


Coordination Compounds Cheat Sheet (Class
12 CBSE)
1 Introduction to Coordination Compounds
• Definition : Compounds with a centr al metal atom/ion bonded to ligands
via coordinate bo nds.
• Centr al Me tal : Tr ansition metal (d-block) with vacant orbitals.
• Ligand : Molecule/ion donating electron pair (e.g., NH
3
, Cl
–
, H
2
O).
• Coordination Number : Number of ligand atoms attached to the centr al
metal.
• Oxidation State : Charge on metal after accounting for ligand charges (e.g.,
Co
3+
in [Co(NH
3
)
6
]
3+
).
2 Types of Ligands
Type Example Description
Monodentate NH
3
, Cl
–
, CN
–
One donor atom
Bidentate C
2
O
2–
4
, eth ylenediamine (en) Two donor atoms
Polydentate ED T A
4–
Multiple donor atoms
Ambidentate SCN
–
(via S or N) Binds via different atoms
Chelating en, ED T A
4–
F orms ring with metal
3 Nomenclature of Coordination Compounds
• IUP A C Rules :
1. Ligands named first (alphabetical, prefixes: di-, tri-, etc.).
2. Metal named with oxidation state in Roman numer als (e.g., cobalt(III)).
3. Anionic complexes end in “-ate”; neutr al/cationic use metal name.
• Example : [Co(NH
3
)
5
Cl]Cl
2
? Pentaamminechlorocobalt(III) chloride.
1
4 Isomerism in Coordination Compounds
• Structur al I somerism :
– Ionization: Different ions in solution (e.g., [Co(NH
3
)
5
Br]SO
4
vs. [Co(NH
3
)
5
SO
4
]Br).
– Linkage: Ligand binds via different atoms (e.g., M SCN vs. M NCS).
– Coordination: Ligands swap between coordination sphere and out-
side.
• Stereoisomerism :
– Geometrical: Cis/tr ans arr angements (e.g., [Pt(NH
3
)
2
Cl
2
]).
– Optical: Non-superimposable mirror images (e.g., [Co(en)
3
]
3+
).
5 V alence Bond Theory (VB T)
• Concept : Metal uses h ybrid orbitals to bond with ligands.
• Hybridization :
– Octahedr al: d
2
sp
3
(inner , low spin) or s p
3
d
2
(outer , high spin).
– Square planar: dsp
2
.
– T etr ahedr al: sp
3
.
• Examples :
– [Co(NH
3
)
6
]
3+
: d
2
sp
3
, diamagnetic.
– [CoF
6
]
3–
: sp
3
d
2
, par amagnetic.
6 Cry stal Field Theory (CFT)
• Concept : Ligands cause d-orbital splitting due to electrostatic inter actions.
• Splitting P atterns :
– Octahedr al: t
2g
(lower), e
g
(higher).
– T etr ahedr al: e (lower), t
2
(higher).
– Square planar: d
x2–y2
highest.
• Crystal Fie ld Splitting Energy (? ) : Energy gap between split orbitals.
• Spectrochemical Series : I
–
<Br
–
<Cl
–
<F
–
<H
2
O<NH
3
<en<NO
–
2
<CN
–
.
• High Spin vs . Low Spin : Depends on? vs. pairing energy .
2
Page 3


Coordination Compounds Cheat Sheet (Class
12 CBSE)
1 Introduction to Coordination Compounds
• Definition : Compounds with a centr al metal atom/ion bonded to ligands
via coordinate bo nds.
• Centr al Me tal : Tr ansition metal (d-block) with vacant orbitals.
• Ligand : Molecule/ion donating electron pair (e.g., NH
3
, Cl
–
, H
2
O).
• Coordination Number : Number of ligand atoms attached to the centr al
metal.
• Oxidation State : Charge on metal after accounting for ligand charges (e.g.,
Co
3+
in [Co(NH
3
)
6
]
3+
).
2 Types of Ligands
Type Example Description
Monodentate NH
3
, Cl
–
, CN
–
One donor atom
Bidentate C
2
O
2–
4
, eth ylenediamine (en) Two donor atoms
Polydentate ED T A
4–
Multiple donor atoms
Ambidentate SCN
–
(via S or N) Binds via different atoms
Chelating en, ED T A
4–
F orms ring with metal
3 Nomenclature of Coordination Compounds
• IUP A C Rules :
1. Ligands named first (alphabetical, prefixes: di-, tri-, etc.).
2. Metal named with oxidation state in Roman numer als (e.g., cobalt(III)).
3. Anionic complexes end in “-ate”; neutr al/cationic use metal name.
• Example : [Co(NH
3
)
5
Cl]Cl
2
? Pentaamminechlorocobalt(III) chloride.
1
4 Isomerism in Coordination Compounds
• Structur al I somerism :
– Ionization: Different ions in solution (e.g., [Co(NH
3
)
5
Br]SO
4
vs. [Co(NH
3
)
5
SO
4
]Br).
– Linkage: Ligand binds via different atoms (e.g., M SCN vs. M NCS).
– Coordination: Ligands swap between coordination sphere and out-
side.
• Stereoisomerism :
– Geometrical: Cis/tr ans arr angements (e.g., [Pt(NH
3
)
2
Cl
2
]).
– Optical: Non-superimposable mirror images (e.g., [Co(en)
3
]
3+
).
5 V alence Bond Theory (VB T)
• Concept : Metal uses h ybrid orbitals to bond with ligands.
• Hybridization :
– Octahedr al: d
2
sp
3
(inner , low spin) or s p
3
d
2
(outer , high spin).
– Square planar: dsp
2
.
– T etr ahedr al: sp
3
.
• Examples :
– [Co(NH
3
)
6
]
3+
: d
2
sp
3
, diamagnetic.
– [CoF
6
]
3–
: sp
3
d
2
, par amagnetic.
6 Cry stal Field Theory (CFT)
• Concept : Ligands cause d-orbital splitting due to electrostatic inter actions.
• Splitting P atterns :
– Octahedr al: t
2g
(lower), e
g
(higher).
– T etr ahedr al: e (lower), t
2
(higher).
– Square planar: d
x2–y2
highest.
• Crystal Fie ld Splitting Energy (? ) : Energy gap between split orbitals.
• Spectrochemical Series : I
–
<Br
–
<Cl
–
<F
–
<H
2
O<NH
3
<en<NO
–
2
<CN
–
.
• High Spin vs . Low Spin : Depends on? vs. pairing energy .
2
7 Stability of Coordination Compounds
• Stability C onstant (ß ) : Higherß = more stable compl ex.
• F actors :
– Strong field ligands (e.g., CN
–
).
– Chelate effect: Bidentate/polydentate ligands (e.g., ED T A
4–
) increase
stability .
8 Importance and Applications
• Analytical C hemistry : ED T A
4–
for metal ion titr ation.
• Biological : Haemoglobin (F e
2+
), chloroph yll (Mg
2+
).
• Industrial : Catalysts (e.g., Wilkinson’ s catalyst), metal extr action (e.g., [Ni(CN)
4
]
2–
).
9 Bo nding in Coordination Compounds
• W erner ’ s Theory : Primary (ionizable) and secondary (non-ionizable) va-
lencies.
• Effective Atomic Number (EAN) : T otal electrons around metal = noble gas
atomic number .
• Magnetic P roperties :
– Diamagnetic: All electrons paired.
– Par amagnetic: Unpaired electrons.
10 Colour in Coordination Compounds
• Cause : d-d electron tr ansitions absorb specific wavelengths.
• F actors : Oxidation state, ligand strength, geometry .
• Example : [Ti(H
2
O)
6
]
3+
appears purple (absorbs green-yellow).
3