3c Flashcards
what can be altered to chnage the 🔺o or 🔺t magnitude
the ligand field strength
which is changed by the identity of the ligand
Oh : ligands approach where
on the axes
Td: ligands approach where
between the axes
what does a free ion mean
theres no ligand field
all the d orbitals are degenerate
when we do the free ion config using he russel saunders STATE TERM,, what do we need to make sure we do
we need to max out the L and S terms
how do we max out the L and S terms for the state term of a free ion
we make sure all the e- have parallel spins + respect pauli
we add e- to the higher ml values!
bc when we add the s’s to form S,, we want it to be large,
when we add the ml values to get L,, we want it to be large.
these are then used to get a state term
what happens when we dont max out L and S
we get a higher eneegry state termm ,, ,aka an excited state term for a free ion (no ligand field)
d2 state term gs, and 2 excited states
d2 = 2 d electrons
1/2 + 1/2 = 1 so spin = 3
2 + 1 = 3 so F
so 3F for ground state
d2 for 1st excited state
1/2 + 1/2 = 1 = 3
ml of 1 + ml of 0 = 1
so L=P
so 3P is an excited state
d2 for 2nd excited state
1/2 - 1/2 = 0 = 1 for multiplicity.
put 2e- in the ml = 2 to get L = 4 = G
so 1G is another excited statw
when dn configurations are symmetry related,, what does this mean
it means that they have the same term symbol!!
what dn configurations are symmetry related,, what does this mea and what things do they have in common
symmetry related = they have the same sterm symbol
bc they have the same number of transitions arising from the ground state split term aka what the d orbitals split into (which is also the same)
what does an orgel diagram do
it represents how d orbitals split due to ligand fields
it plots ligand field strength against energy
it predicts the spin allowed (🔺S=0) d-d transitions for each dn configuration
d1 config: predict the ground state term for the free ion
s = 1/2 so S = 2
l = +2 so L = 2 = D
so 2D = term symbol for gs d1.
J = L-S = 2-0.5 = 1.5.
orgel diagram for d1
🔺x along the x axis meaning the more u move to the right,, the larger the ligand field spliiting energy meaning the larger the gap between the 2 groups of orbitals (the transtion energy)
on the y axis u have energy, which shows the enrgy difference between the upper and lower groups of orbitals!!!
u have 2D on the lhs on the lhs of the axis: u then have this split up and down. with 2Eg higher in energy and 2Tg lower in energy. with 0.6🔺o on the upper gap and 0.4🔺0o on the lower gap.
the 2Eg and 2T2g are the 2 states predicted using group theory.
this means for octahedral d1, the orgel diagram predicts ONE d-d band in the abs spectrum, which is seen by one peak in the spec.
this peak has a hard shoulder but thats calm for now.
what is the significance of the 2 states having 2T2g and 2Eg as their labels
they both have a superscript of 2. meaning they have the same spins meaning these are spin allowed transitions bc 🔺S = 0.
if the x axis of an orgel diagram is 🔺x: the lhs and rhs will correspond to what
lhs = weak field ligand,, small 🔺x.
rhs = strong field ligand = larger 🔺x.
what does the wavelength of the abs correspond to
it corresponds to the identity of the ligand and therefore its ligand field strength.
which can be seen using the spectrochemical series.
what is the transition for D1 for Td if the Oh transition was 2T2g –> 2Eg
the transition for Td will now be 2E –> 2T2
bc the spin is thr same bc wrre not changing the e- configuration,, just the order of the orbitals. aka the e and t orbitals swap when going from T to O etc.
how many bands does the d1 config for Td predict if the d1 config for Oh predicts 1 band.
the Oh predicts one band: 2T2g to 2Eg whiile the tetrahedral one will also have 1 band as its prediction,, but it will be the inverse of the Oh one.
it will have 2E –> 2T2 bc obvs theyre switching.
0,4🔺t will be the higher split and 0.6🔺t will be the lower split.
d1 and d9 are related by what
theyre related by hole formalism
whats hold formalism in terms of d1 and d9
the fact that d9 is derived from d10,, by replacing an e- with a positive hole which inverts the relative stability of the states.
aka 1 hole and 9 e- vs 1 e- and 9 holes.
when e- fill majority // more than half of the ml orbitals,, how do we find J
normally = J = L-S
if most are full: J = L+S
what do d1 and d9 have in common
same ground state term symbol (2D)
same states under Oh symmetry (2T2g and 2Eg)
same number of predicted transitions.
when can multiple d configs be put on one orgel diagram
when they have the same L value for their term symbol.
d1 d4 d6 and d9 all have a D config. so they can be put on an orgel diagram.
describe the combo of d1 d4 d6 and d9 orgel diagram due to them all sharing // having a D L value for their term symbols
its an ‘x’ marks the spot x.
with energy on the y axis..
d1 and d6 are friends
d4 and d9 are friends
u have d1 and d6 Td and d4 and d9 Oh on the LHs.
u have d1 and d6 Oh and d4 d9 Td on the rhs.
and then u have Eg or E (lower left or upper right) orrrrr T2g or T2(upper left or lower right) on the cross.
d1 and d6 areeee
treated the same
