4: crystal field theory

Question 1

what does crystal field theory assum?

Answer 1

1. transition metal ion is free metal cation by itself
2. ligand has point charges (-)
3. the force btw them is electrostatic force (ionic)
   => creating electrostatic field (crystal field)

Question 2

3 factors affecting crystal splitting, Δo

Answer 2

1. oxidation state of metal ion: greater oxidation state, great Δo
2. metal size: larger metal (even if = oxdiation state), greater Δo
3. nature of ligand: look @ spectrochemical series

Question 3

how does our eyes perceive color?

Answer 3

our eyes perceive color as complimentary /opp/ of what is absorbed by complex

Question 4

_____ Δo corresponds to absorption of _____ energy light w/ _____ wavelength

Answer 4

smaller / smaller / smaller

Question 5

what goes in the productin of compelx?

Answer 5

transition mental bind linkages to fo0rm complex

linkage = any molec/ion bonded to a metal centre e.g NH3-Ti
complex = any compound of several atoms and at least 1transition metal

Question 6

distinct 3 types of linkage: monodentate ligand vs bidentate ligand vs polydentate ligand

Answer 6

monodentate: has 1 donor atom bonded to a metal centre e.g NH3-Ti
bidentate: 2 donor atoms
polydentateL multiple donor atoms

Question 7

coordination isomer vs ionization isomer

Answer 7

when 2 complexes differ by which…

1) transition metal are cation
2) counterions are anionic ligand

Question 8

when 2 complexes differ by which atom in ligand is the donor atom; created from ambidentate ligand

Answer 8

linkage isomerism

Question 9

is stereoisomer possible with complex?

Answer 9

yes, cis or trans isomers

Question 10

list VSPER for each coordination complex?

Answer 10

2- linear
3- trigonal planar
4- tetrhedral and square planar
5- trig bipyramidal and swaure pyramydal
6- octahedrao and distorted octahedraln

Question 11

what is d orbital splitting in crystal field?

Answer 11

octahedral crystal field has a free atom with 5 degenerate d- orbitals

in d orbital of octahedral complex, splits into
- higher energy lvl = eg orbitals point @ point charge => repulsion !! c-> destabalized
- in lower energy leveloo - t2g lies btw ligand =>less repulsion -> stabilized

Question 12

what is spectrochemical series?

Answer 12

I- -> Br- (small Δo, weak field ligand) —–> CO (large Δo, strong field ligand)

Question 13

what happens when a complex absorb light?

Answer 13

when a complex absorbs light,
e- excited from t2g -> eg
via d-d transition

smaller Δo corresponds to absorption of smaller energy light w/ smaller wavelength

Question 14

what of magnetism in transition metal complex?

Answer 14

the most stable arrng. depends on Δo and pairing energy

if Δo<pariing energy, high spin configura is favoured
if Δo > pairing energy, low spin…

high spin: low Δo, half filled
low spin: large Δo, fully filled