Test 3 Flashcards
What type of field do 1st row trans. metals form?
Weak.
What are normal oxidation numbers for the 2nd and 3rd rows of the trans. metals?
Early trans. metals have max valance oxidation #s. O.N. decrease across
What type of field do 2nd and 3rd row trans. metals make?
strong field.
What are trends for CN?
First row can make all kinds of CN. 2nd and 3rd row are usualky form octahedral or square planar. Early metals form mostly octahedral while late trans metals vary
What metals make octehdral, tetrahedral or square planar molecles?
All metals (1-3rd rows) can make tetrahedral if they have 6 ligands. Only first row will make tetrahedral if it has 4 ligands. Any metal with d8 electrons can form square planar if it has 4 ligands.
What are the crystal field diagrams for octahedral, tetrahedral and square planar?
Octahedral: 3 orbitals on the bottom and 2 on top
Tetrahedral: 2 orbitals on the bottom and 3 on top
Square planar: 5 orbitals at 4 levels and only the bottom level has 2
What is the spectrochemical series from molecule that makes the most weak field complex to strong field complex. Which are sigma and which are pi donors?
Halides< O donors < N donors < C donors
I<f>2-<h>2O<oh->3<pph>3<co></co></pph></oh-></h></f>
<p>sigma--> pi</p>
</co></pph></oh-></h></f>
How do I know when a complex is high spin or low spin?
Big energy gap b/w energy levels=strong field=low spin
Small energy gap b/w energy levels=weak field=high spin
What things determin weak or strong field?
What complexes are always weak?
What complexes are always strong?
- High or low spin
- Charge; 3+ is boarder line
- Bonding ability of ligand (spect. series)
Tetrahedral are always weak
2nd and 3rd rows are always strong (so only 1st row varys)
How do you find the spin multiplicity?
Spin multiplicity=2S+1= # of unpaired e- + 1
What are the reasons behind paramagnetic, diamagnetic, ferromagnetic, and antiferromagentic properties?
How are they temperature dependent?
Paramagnetic=attracted to mag field since it has unpaired electrons. Magnetic suseptibilty deacrease with increasing temp
Diamagnetic= repelled by mag field b/c all pair e-. Not dependent on temp
Ferromagnetic= all e- line up with mag. field to strongly attraced. Mag. sus. decreases with increasing temp
Anitferromagnetic=all electron pairs go against mag field. Increases with increasing temp
What is the spin selection rule?
It says that only transitions to orbitals with the same spin multiplicity are allowed
What is the Laporte selection rule?
It says that transitions between states that have the same symmetry w/ respect to inversion are not allowed. (no little gā>little g) This means only Tetrahedral are laport allows and no octahedral complexes for us now are
What is a Jahn Teller distortion?
what d e- count will not show distortions and which will show strong distortions?
It is a distortion in orbital shaoe due to incomplete energy levels
d3, d6 strong field , d5 weak field, d8
d4 weak field, d7 strong field, d9
What should I make sure not to forget when listing possible d-to-d transitions?
spin multiplicity and little g for octahedral complexes
What are the important extinction coefficients I need to remember?
For spin and laporte forbidden: < 1
for spin allowed but laport forbidden: 1-10 or 100
spin and laport allowed: 100-500
What should i remember when reading T-S diagrams?
Ground state is different for weak field complexes so make sure i am looking at the right one. For weak field, do not use the first, identical transition (its the same thing)
What is the dissociative mechanism?
Associative?
Dissociative is like Sn1; ligand-metal complex disociates before forming a new bond
associative is like Sn2 where and intermediate containing all complexes is formed
What are the inner and outer sphere mechanisms?
Inner sphere mechanism involves a bridging ligand during a redox reaction where ligands switch
outer sphere mechanism does not involve a bridging ligand
How do you find the spin only magnetic moment?
2 mui sqrt(S(S+1))
where S is half the total # of e-
