Electronic and Magnetic Properties of the f-block

Question 1

sources of electric fields

Answer 1

electric currents and spin magnetic moments of elementary particles

Question 2

Hund’s 3rd rule

Answer 2

orbitals greater than half filled, highest J = ground state
orbitals less than half filled, lowest J = ground state

Question 3

why Ln weak UV bands

Answer 3

small difference in energy levels,

Question 4

Ln luminescence

Answer 4

direct excitation hindered by narrow adsorption bands
indirect excitation = UV promoted e- to excited singlet state, non-radiative ISC to excited triplet state, further ISC to Ln3+ excited state which relaxes via fluorescence

Question 5

Why is the Lande equation poorly applied to the Actinides

Answer 5

complications due to mixing of states and presence of low lying excited states

Question 6

NMR of Ln

Answer 6

Ln shift reagents added to diamagnetic samples and induce chemical shift changes via through space interactions

Question 7

requirements of Ln shift reagents

Answer 7

need to be able to coord to heteroatom, chiral allows determination of ee by integration

Question 8

MRI basis

Answer 8

essentially a big NMR machine, contrast due to different relaxation times of water, H atoms with short relaxation times give brighter images, Gd3+ complexes used to enhance images

Question 9

Gd3+ requirements for MRI

Answer 9

complex that’s soluble in physiological media, must be strongly bound to prevent toxicity and needs at least one free coord site for water