Coordination Chemistry: CFT, LFT, Spectra, Magnetism

50 lessons, pages 3261–3310.

  1. Coordination Chemistry at University Level — From qualitative splitting to quantitative bonding, spectra and magnetism
  2. Crystal Field Theory Revisited: The Point-Charge Model — Electrostatic origin of d-orbital splitting and its assumptions
  3. d-Orbital Splitting in Lower Symmetries — Tetragonal, square-planar, trigonal-bipyramidal and square-pyramidal fields
  4. Point Groups and Symmetry Labels for d Orbitals — Using Oh and Td character tables to label t2g, eg, e and t2
  5. The Spectrochemical Series Explained — σ-donor, π-donor and π-acceptor ligands and their effect on Δ
  6. Metal Dependence of Δ — Oxidation state, period and the 4d/5d enhancement
  7. Ligand Field Theory: Why Go Beyond Crystal Fields? — Evidence for covalency in metal–ligand bonding
  8. Ligand Group Orbitals in Octahedral Complexes — Building symmetry-adapted combinations of ligand σ orbitals
  9. The σ-Only Octahedral MO Diagram — Bonding, non-bonding t2g and antibonding eg* levels
  10. π-Donor Ligands in the MO Picture — How halides and oxide raise t2g and shrink Δo
  11. π-Acceptor Ligands and Back-Bonding — CO, CN⁻ and phosphines lowering t2g and enlarging Δo
  12. The Angular Overlap Model — Parameters eσ and eπ for estimating orbital energies
  13. MO Diagrams for Tetrahedral and Square-Planar Complexes — Ligand field splittings beyond octahedral geometry
  14. The Jahn–Teller Theorem — Why degenerate electronic states in non-linear molecules distort
  15. Jahn–Teller Distortions in Copper(II) and High-Spin d⁴ — Tetragonal elongation, compression and their energetic basis
  16. Strong and Weak Jahn–Teller Effects — eg versus t2g degeneracy and structural evidence
  17. Dynamic Jahn–Teller Effects and Spectroscopic Signatures — Fluxional distortions, broadened bands and EPR behaviour
  18. Free-Ion Terms: Russell–Saunders Coupling — Combining orbital and spin angular momenta into L and S
  19. Deriving Term Symbols for dⁿ Configurations — Microstate tables and the terms of d² as a worked case
  20. Hund's Rules and Ground-State Terms — Identifying ground terms for d¹ to d⁹ ions quickly
  21. Racah Parameters and Interelectron Repulsion — B and C as measures of term separations
  22. Splitting of Free-Ion Terms in Octahedral Fields — How S, P, D, F and G terms correlate with Oh states
  23. Selection Rules for Electronic Transitions — Spin and Laporte rules and how they are relaxed
  24. Band Intensities and Band Widths — Molar absorption coefficients and vibronic broadening
  25. Orgel Diagrams for d¹, d⁴, d⁶ and d⁹ — Single spin-allowed transitions from D ground terms
  26. Orgel Diagrams for d², d³, d⁷ and d⁸ — Three spin-allowed bands from F ground terms
  27. Introducing Tanabe–Sugano Diagrams — Axes E/B versus Δo/B and the ground-state baseline
  28. Reading Tanabe–Sugano Diagrams for d² — Assigning the bands of [V(H₂O)₆]³⁺
  29. Using Tanabe–Sugano Diagrams to Find Δo and B — The band-ratio method for extracting ligand field parameters
  30. Tanabe–Sugano Diagrams for d³ and d⁸ — Chromium(III) and nickel(II) spectra analysed
  31. Spin Crossover Points on Tanabe–Sugano Diagrams — The discontinuity for d⁴ to d⁷ and changes in ground state
  32. Spin-Forbidden Bands and the Spectrum of Manganese(II) — Why high-spin d⁵ complexes are so pale
  33. The Nephelauxetic Effect — Reduction of B in complexes as evidence for covalency
  34. Charge-Transfer Spectra — LMCT and MLCT bands and their intense colours
  35. Spectra of Tetrahedral Complexes — Why cobalt(II) tetrahedral species absorb strongly
  36. Interpreting a Complete Electronic Spectrum — Combining d–d, spin-forbidden and charge-transfer assignments
  37. Origins of Magnetism in Complexes — Spin and orbital angular momentum as sources of magnetic moments
  38. Magnetic Susceptibility and Its Measurement — Gouy, Evans NMR and SQUID methods in principle
  39. The Curie Law and Curie–Weiss Behaviour — Temperature dependence of paramagnetic susceptibility
  40. Diamagnetic Corrections and Effective Moments — From measured susceptibility to μeff
  41. Orbital Contribution and Quenching — When T ground terms give moments above spin-only
  42. Spin–Orbit Coupling and Deviations from Spin-Only Moments — The λ correction for A and E ground terms
  43. Magnetism of Lanthanide Ions — Why J rather than S governs 4f moments
  44. Spin Crossover in Depth — Thermal, pressure and light-induced spin-state switching
  45. Magnetic Exchange in Polynuclear Complexes — Ferromagnetic and antiferromagnetic coupling via bridging ligands
  46. Superexchange and Copper(II) Acetate — The coupling constant J and singlet–triplet gaps
  47. Single-Molecule Magnets — Spin ground states, anisotropy and slow magnetic relaxation
  48. Linking Structure, Spectra and Magnetism — Using combined data to deduce geometry and spin state
  49. Integrated Problems in Ligand Field Chemistry — Multi-step problems combining MO theory, spectra and moments
  50. Coordination Chemistry: CFT, LFT, Spectra, Magnetism: Unit Review — Key ideas, connections and exam strategies for the whole unit