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Colour :lower_left_paintbrush: :rainbow: - Coggle Diagram
Colour :lower_left_paintbrush: :rainbow:
Electronic spectra
UV Vis - we will be looking at 2 different spectra. this will be in the UV and Visible regions.
one thing to remember is that we work with complimentary colors.
2 different spectra
Charge transfer spectra
these are intense absorptions (see bright colour)
use extinction coefficient (Beer Landa Law)
equation
- basically to use to determine the allowed-ness
tends to be in UV but tails off in the visible region.
[MnO4]- a d0 thus we see charges transfer between metal and ligand
LMCT
corresponds to the reduction (gain) of electrons
common in metals that can be reduced or in ligands that can be oxidised.
example: TiI4
MLCT
corresponds to the oxidation of a metal and the reduction of a ligand
typically found in complexes where the ligands have low lying empty pie-acceptor orbitals.
example Ti(bippy)3
close to "non-innocent" behavior
Annotate the transitions
:clock2:Ligand field spectra
involves the charge transferee between d-orbitals
Colour Vs Intensity
Intensity is how bright a colour is, not what the colour is. Energy is the same but the intensity is different.
Intensity is goverened by different things.
intensity has to do with the alowed-ness of the electronic transition
colour is colour (red vs blue)
Quantum numbers
Recap: n L ML s
microstates
(look at 2p2 example drawn below)
microstates only have the same energy if repulsions are negligable (but atoms & molecules are compact thus we can not ignore)
group all of the same energy states together
end up with
Terms
a spectroscopically distinguishable energy levels and we look at the transitions between these
Terms
for 3d series (lightest series) we need to consider: the spin of the electron and the orrientation of the anguar momentum
when we get down to the heavier d series wee see the coupling (just need to know)
can group all the spins to get the
Total spin quantum number
Total orbital angular momentum
Russel Saundres coupling
Russel Saundres scheme
we neek to know what values of L and S can arrise in atom
apply the
Clebsch Gordan series
Spin coupling:
S = (s1 + s2+ s3...)+(s1+s2+s3..-1)+ (s1+s2+s3...-2)+...
S must be positive or 0
Orbit-Orbit coupling
same idea for L
The value of L determins an energy state for a system of electrons defined by term letters:
L(orbital A) l 0 l 1 l 2 l 3 l 4 l 5 l
Term letter l S l P l D l F l G l H l
Quantum no. ML and Ms
these quantum no gives the orientation of of the angular momentum relative to arbitrary axis
actual values of ML and MS for given microstates found easily by adding values of ml and ms for individual electrons
Equation to find microstates
Spin-spin coupling > Orbit-orbit coupling > Spin-orbit coupling
Spin selection rule
Can be relaxed by spin-orbit coupling
Add diagram
Orbit (laport) selection rule
L = +/- 1
in a central semetric molecule/ ion the only allowed transition are those that are accompaniede by a change in party. (it has a center of inversion)
Spin & Laport values