CSIR NET Coordination & Organometallic Chemistry Handwritten Notes (Free PDF)
Master the most crucial, high-weightage unit of Inorganic Chemistry. Download complete topper-curated class notes covering CFSE formulas, Jahn-Teller distortion, 18-electron counting rules, Wade’s clusters, and catalytic mechanisms.
📥 INSTANT PDF DOWNLOAD- 1. Syllabus Breakdown & Exam Weightage Analysis
- 2. Coordination Chemistry: Key Formulas & Spectrochemical Series
- 3. Jahn-Teller Distortion (JTD) High-Yield Summary
- 4. Organometallic Chemistry: 18-Electron Rule & M−M Bond Formulas
- 5. Wade-Mingos Rules & Skeletal Electron Pair Theory
- 6. Industrial Catalysis: Wilkinson, Monsanto & Wacker Cycles
- 7. Solved CSIR NET Part-C Practice Question
- 8. Frequently Asked Questions (FAQs)
📊 1. Syllabus Breakdown & Exam Weightage
In CSIR UGC NET Chemical Science and GATE (CY), Inorganic Chemistry accounts for roughly 60 to 75 marks. Coordination compounds along with organometallic chemistry consistently contribute 35 to 45 marks across Part B and Part C.
| Module Name | Question Type | Expected Marks | High-Frequency Core Topics |
|---|---|---|---|
| Coordination Chemistry | Part B (2 marks) & Part C (4 marks) | 18 – 24 Marks | CFT, CFSE, Spinels, Electronic spectra (Orgel & Tanabe-Sugano), Magnetic properties, Trans effect |
| Organometallic Chemistry | Part B & Part C | 16 – 22 Marks | 18-electron counting, M−M bonds, Wade’s rules, Isolobal analogy, Wilkinson & Wacker catalysis |
| Reaction Mechanisms | Part C (Analytical) | 8 – 12 Marks | Inner-sphere vs Outer-sphere ET, Dissociative (D) & Associative (A) pathways |
🔬 2. Coordination Chemistry: Key Formulas & Series
In octahedral complexes, d-orbitals split into degenerate t2g (stabilized by −0.4 Δo) and eg (destabilized by +0.6 Δo). In tetrahedral fields, the order inverts without the “g” subscript:
Tetrahedral Splitting Relationship: Δt = (4/9) Δo ≈ 0.44 Δo
I− < Br− < S2− < SCN− < Cl− < NO3− < F− < OH− < C2O42− < H2O < NCS− < edta4− < NH3 < en < bipy < phen < NO2− < PPh3 < CN− ≈ CO
CN− ≈ CO ≈ C2H4 > PR3 ≈ H− > CH3− > C6H5− > I− ≈ SCN− > Br− > Cl− > Py > NH3 > OH− > H2O
⚡ 3. Jahn-Teller Distortion (JTD) Reference Matrix
The Jahn-Teller theorem dictates that non-linear molecules with orbitally degenerate ground states distort to lower overall symmetry and lift degeneracy:
| Configuration | Spin State | Electronic Occupancy | Distortion Type | Representative Example |
|---|---|---|---|---|
| d1, d2 | High / Low | t2g1, t2g2 | Weak (Dynamic JTD) | [Ti(H2O)6]3+ |
| d3, d8 | High / Low | t2g3, t2g6eg2 | No Distortion | [Cr(H2O)6]3+, [Ni(H2O)6]2+ |
| d4 (HS) | High-Spin | t2g3eg1 | Strong (Static JTD) | [Cr(H2O)6]2+, [Mn(H2O)6]3+ |
| d7 (LS) | Low-Spin | t2g6eg1 | Strong (Static JTD) | [Co(NH3)6]2+ |
| d9 | High / Low | t2g6eg3 | Very Strong (Tetragonal z-out) | [Cu(H2O)6]2+ |
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📥 FAST DOWNLOAD PDF⚙️ 4. Organometallic Chemistry: 18-Electron Rule
| Ligand | Formula | Neutral (Covalent) Method | Ionic (Charge) Method |
|---|---|---|---|
| Terminal Halide / Hydride | −X, −H | 1 e− | 2 e− (X−, H−) |
| Bridging Halide | μ2−X | 3 e− | 4 e− (X−) |
| Carbonyl / Phosphine | −CO, −PR3 | 2 e− | 2 e− (neutral) |
| Nitrosyl (Linear) | −NO (180°) | 3 e− | 2 e− (NO+) |
| Nitrosyl (Bent) | −NO (≈ 120°) | 1 e− | 2 e− (NO−) |
| Allyl System | η1-allyl / η3-allyl | 1 e− / 3 e− | 2 e− / 4 e− (anion) |
| Cyclopentadienyl | η5-C5H5 (Cp) | 5 e− | 6 e− (Cp−) |
Total M−M Bonds = [18 × n − TVE] / 2
M−M Bonds Per Metal Atom = 18 − (TVE / n)
🔷 5. Wade-Mingos Rules & Skeletal Electron Pairs
To classify metal cluster and borane architectures (where n = number of vertices/metal atoms):
| Structure Classification | Skeletal Electron Pairs (SEP) | Formula Framework | Polyhedron Geometry |
|---|---|---|---|
| Closo | n + 1 | BnHn2− | Complete deltahedron (e.g., Octahedron, Icosahedron) |
| Nido | n + 2 | BnHn+4 | Closo cage missing 1 vertex |
| Arachno | n + 3 | BnHn+6 | Closo cage missing 2 vertices |
| Hypho | n + 4 | BnHn+8 | Closo cage missing 3 vertices |
| Klado | n + 5 | BnHn+10 | Closo cage missing 4 vertices |
🔄 6. Industrial Catalysis: Reaction Cycles Comparison
| Catalytic Name | Catalyst / Active Form | Key Elementary Steps | Crucial Rate-Determining Step |
|---|---|---|---|
| Wilkinson’s Hydrogenation | RhCl(PPh3)3 → [RhCl(PPh3)2] (14 e−) | Oxidative Addition of H2 → Alkene coordination → Migratory insertion → Reductive elimination | Migratory insertion of hydride into coordinated alkene |
| Monsanto Acetic Acid | [Rh(CO)2I2]− (16 e−) | Oxidative addition of CH3I → CO migratory insertion → Reductive elimination of acetyl iodide | Oxidative addition of methyl iodide (CH3I) to Rh(I) |
| Wacker Oxidation | [PdCl4]2− / CuCl2 | Ethylene coordination → Nucleophilic OH− attack → β-hydride elimination → Reductive elimination | Reoxidation of Pd(0) to Pd(II) by Cu(II) co-catalyst |
| Hydroformylation (Oxo) | HRh(CO)(PPh3)3 or HCo(CO)4 | Alkene coordination → Insertion into M−H → CO insertion → Hydrogenolysis (Acyl to Aldehyde) | Hydrogenolysis / Reductive elimination of aldehyde product |
📝 7. Solved CSIR NET Part-C Practice Question
Question: Find the total number of Metal−Metal (M−M) bonds in the cluster [Co4(CO)12] and the number of bonds per cobalt atom.
Step-by-Step Solution:
- Calculate Total Valence Electrons (TVE):
Cobalt (Group 9) × 4 atoms = 4 × 9 = 36 e−
Carbonyl (−CO) ligands = 12 × 2 = 24 e−
TVE = 36 + 24 = 60 e− - Apply the M−M bond formula for n = 4 metal atoms:
Total M−M Bonds = [18 × n − TVE] / 2 = [18(4) − 60] / 2 = [72 − 60] / 2 = 6 M−M Bonds. - Calculate M−M bonds per metal atom:
Bonds per metal = 18 − (TVE / n) = 18 − (60 / 4) = 18 − 15 = 3 Bonds/Metal.
Conclusion: [Co4(CO)12] forms a tetrahedral metal core with 6 total Co−Co edges, where each Cobalt atom is bonded to 3 neighbors.
❓ 8. Frequently Asked Questions (FAQs)
Yes. These notes cover the entire syllabus for Coordination and Organometallic Chemistry. Once you thoroughly master the mechanisms and formulas in these notes, complement your study by solving the past 10 years of CSIR NET and GATE PYQs.
A linear M−N−O bond angle (180°) donates 3 electrons in the neutral method (NO+ donor), whereas a bent M−N−O bond angle (~120°) donates 1 electron (NO− donor). Examine infrared IR stretching frequencies: linear NO absorbs at ~1800–1900 cm−1, while bent NO absorbs at ~1525–1650 cm−1.
Trans influence is a ground-state thermodynamic property reflected in longer metal-ligand bond lengths (measured via X-ray crystallography). Trans effect is a kinetic property reflecting substitution rates influenced by stabilization of the trigonal bipyramidal transition state via π-backbonding.
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