Advanced Organometallic and Coordination Chemistry

What is the UV-vis reigons?

10 000 - 50 000 cm^-1

→ Reigon where electronic excitations usually occur

Why is UV-vis wavelength reigon the reigon where electronic excitations occur?

• Ligand spectra

• Counter-ion spectra

• Charge-transfer spectra

• Ligand-field spectra → (d-d transitions)

What are the selection rules?

• Δ S = 0

• Δ L = ± 1

• Laporte rule - In a centrosymmetric system, transitions are forbidden ( g → g or u → u)

→ e.g = s → p and p → d aren’t allowed

Why is it complicated to use electronic spectra to determine the number of transitions for more than one electrons?

Ignores the effect that other electrons have

What do you use Russell-Saunders coupling for?

Derive terms arising from dⁿ configurations → Ground state term (and maybe first excited state term)

How do you work out Russell-Saunders coupling to work out ground state terms?

How do you draw out orgel diagrams to determine the number of transitions (use d¹ as an example)

What is hole formalism?

Figuration with one hole = Opposite to configuration with one electron

→ Or d¹ is the opposite to d⁹

• dⁿ = dⁿ⁺⁵

How and why does energy level diagram for a d²,d³,d⁷,d⁸? configuration lead to a semiquantitative Tanabe Sugano diagram?

Energy now depends on:

• Crystal field splitting parameter (Δ)

• Separation between ³F and ³P (and how they can vary with Δ

• Magnitude of interaction between ³T_1g(F) and ³T_1g(P)

What are the energies of the 4 levels for d²,d³,d⁷,d⁸? (DONT NEED TO REMEMBER)

What are Racah Parameters?

In the free ion, they are parameters that describes electron-electron repulsion

How do you work out the energy gaps between states for d electrons?

Use sums of multiples of B and C parameters

How do you work out the energy gap between states of the same multiplicity?

Only use multiple of B

What is the Nephelauxetic effect?

Greater the reduction in the Racah B parameter, the greater the covalency in the M-L bond

How do you calculate the Nephelauxetic ratio?

What is the order of the Nephelauxetic series?

Very different to the spectrochemical series

How do you calculate the Racah B parameter and crystal field splitting parameter (Δ) starting from transition energy formulas using d² and d⁷ as an example?