Crystal Field Theory

Question 1

isomers

Answer 1

same formula, different properties

Question 2

isomers divide into?

Answer 2

structural isomers (different bonds) and stereoisomers (same bonds, different arrangements)

Question 3

structural isomers divide into?

Answer 3

coordination-sphere isomers and linkage isomers

Question 4

stereoisomers divide into?

Answer 4

geometric isomers and optical isomers

Question 5

structural isomers

Answer 5

linkage, hydration, ionisation, coordination

Question 6

linkage isomers

Answer 6

a single ligand has two or more donor atoms and can attach in more than one way eg. SCN

Question 7

hydration isomers

Answer 7

water swaps with a ligand

Question 8

ionisation isomers

Answer 8

change of anionic ligands with counter anions

Question 9

coordination isomers

Answer 9

both a complex anion and cation are present - multiple combinations of ligands with two metal centres

Question 10

geometric isomers

Answer 10

cis: identical ligands are adjacent
trans: identical ligands are on opposite sides of a metal centre
fac: three identical ligands on one side of an octahedral
mer: identical isomers lie around the meridian (two on one side, one adjacent)

Question 11

optical isomers

Answer 11

occur commonly when there is more than one bidentate ligand

non-superimposable mirror images

Question 12

colour - how does it happen and exceptions?

Answer 12

electrons in partially filled d-orbitals absorb visible light and move to d-orbitals with slightly higher energy
Sc3+, Ti4+, Zn2+ are exceptions (filled or empty d-subshells)

Question 13

paramagnetic

Answer 13

attracted to a magnetic field (unpaired electrons)

Question 14

ferromagnetic

Answer 14

if electrons are aligned in the same direction

Question 15

diamagnetic

Answer 15

not magnetic (paired electron spins)

Question 16

crystal field theory

Answer 16

explains stability, colour and magnetism but not metal-ligand bonding
describes how energies of d orbitals on the metal are affected as ligands approach

note: complexes result in electrostatic attractions between metal cation and negative charges on lone pairs on ligands (not covalent)

Question 17

what happens to the energy of the metal d-orbitals when 6 ligands approach?

Answer 17

ligands can approach directly (alone x,y,z axes) or between axes
directly results in greater ligand, d-orbital repulsion and therefore take more energy to form

Question 18

eg orbitals

Answer 18

direct head-to-head repulsion (more unstable). dz^2 and dx^2-y^2

Question 19

t2g orbitals

Answer 19

tangible repulsion leads to lower energy for dxy, dxz and dyz orbitals

Question 20

what is the energy difference between eg and t2g orbitals?

Answer 20

delta oct or delta o