CHEM214 Flashcards
What are all of the d orbital labels?
dxy, dxz, dyz, dz^2, dx^2-y^2
How many d orbitals are there?
5
Which orbitals are negative in dxy?
those between the x&y axis
Which orbitals are negative in dxz?
lobe on the top right along that diagonal
Which orbitals are negative in dyz?
lobe on the top left and along diagonal
Which orbitals are negative in dx^2?
central lobe
Which orbitals are negative in dx^2-y^2?
along the y axis
How are negative orbitals presented in diagrams?
shaded = negative
What is the difference between shielding and penetration?
shielding = the inner shell core e- shield the nucleus, penetration = the outer e- penetrate the inner shells
What electrons does shielding affect? Why?
- 1s has high ed so shields the 3d e- (and the rest of the orbitals) from the nucleus
- 2s shields 3d from the nucleus because the 3d maximum lies outside the 2s maximum
- the 4s does NOT shield 3d from the nucleus much because it is penetrating
- all s orbitals penetrate the core
- 4f electrons DO NOT shield 5s
What electrons does penetration affect?
- the 3d penetrates the 2s
- 3d penetrates 4s very effectively due to lower principle quantum number and the 3d maximum lying inside the 4s maximum
- the 4s penetrates the core very effectively
How does shielding and penetration depend on radial maxima?
- shielding occurs when the maximum of one orbital lies within the maximum of another
- small peaks in ed close to the nucleus allow an orbital to penetrate the core
- the higher the principle quantum number the less shielding an orbital is
What is the effect of penetration?
- the outer electrons experiencing a higher than expected effective nuclear charge, which decreases the orbital energy
- the orbital doing the penetrating decreases in energy
Does 3d or 4s fill first?
4s bc it’s at a lower energy
What makes a transition metal a transition metal?
Its partially filled d shell
What is the effect of a half-filled d shell?
extra stability
Are 4s or 3d electrons lost first upon ionisation? Why?
4s bc at a higher energy due to the 3d penetrating the 4s so the 3d are at a lower energy
What is the d-electron count?
the same as valence electron count - total of all electrons in the 3d and 4s orbitals
Equation for d-electron count?
group number - oxidation state
What are the pseudo transition metals? Why?
Sc, Cu and Zn, Cu has an incomplete d shell, but their chemistry is treated as if they are
What is effective nuclear charge?
the amount of nuclear charge seen by an electron in that orbital
What does the effective nuclear charge depend on?
the principle quantum number, shielding, and penetration
What is the effect of the effective nuclear charge?
as Zeff increases, the orbital energy decreases
What is the effect of shielding?
the Zeff of the e- being shielded decreases, so orbital energy increases
What is the pattern of ion size across a period? Why?
ionic radius decreases across a period bc the Zeff increases
Why do Mn, Fe, and Ni have higher ionic radius than expected?
effect of the partially filled d shell
Why do 2nd and 3rd series elements have similar ionic radii?
lanthanide contraction - poor shielding of 5d e- by 4f`as the 4f orbitals are too diffused, 5d penetrate 4f very effectively so 5d has higher Zeff and contracts
Are ligands lewis acids or bases?
lewis bases (electron pair donors)
Are the metal atoms lewis acids or bases?
lewis acids (electron pair acceptors)
How many electrons do the donor groups of ligands donate?
2
What is the acetonitrile ligand?
MeCN
What is the cyano ligand?
[CN-]
What is the thiocyanate ligand?
[NCS]-
What is the denticity?
the number of bonded groups in a ligand
How many e- donated for bidentate ligands?
4e-
Equations for calculating number of e- donated by a ligand?
=denticity2
OR
=number of donor groups2
What is the hapticity?
The number of atoms in the ligand, bonded to the metal
How do pi-bonded benzene and sigma-bonded Ph donate different no. of e-?
pi-bonded benzene = 2e- from each bond = 6e-
sigma-bonded Ph = 2e- only from one of the C not the C=C
Charge of ammonia?
zero
What is triethylphosphite?
P(OEt)3
Charge of ethyl and phenyl?
-1
What is polarizability?
how easy it is to distort the electron distribution/cloud of the donor
Equation for charge density?
= charge/SA
how polarisable is a hard ligand?
non polarisable (small, with a high charge, high oxidation state)
how polarisable is a soft ligand?
highly polarisable (large, with a low charge, low oxidation state)
What is the pattern with charge density and polarity?
higher charge density = the atom/ion is less polarisable and more polarising
Are oxygen donors hard or soft?
hard
Are phosphorus and sulfur donors hard or soft?
soft
Is nitrogen hard or soft?
depends: ammonia = hard, pyridine = intermediate/soft (part of an unsaturated system)
What are the typically hard metal ions?
first series TM with (III) oxidation state except Mn(II), Zn(II), and Ti(IV), Hf(IV), V(IV)
Why is Ti(IV) a hard metal ion?
half-filled d shell (d5)
What are the typically hard ligands?
F & Cl, H2O, [OH]-, ROH, R2O, [RCO2]-, [SO4]2-, [NO3]-, NH3, RNH2
What are the typically intermediate metal ions?
1st series TM: Fe(II), Co(II), Ni(II), Cu(II)
Rh(III), Ir(III), Ru(III), Os(III)
What are the typically intermediate ligands?
Br-, pyridine, [NCS]- = when binding through N
What are the typically soft metal ions?
Cu(I), Ag(I), Au(I), Hg(II), Cd(II), Pd(II), Pt(II)
What are the typically soft ligands?
I-, [CN]-, CO, PR3, RSH, R2S, [NCS]- = when binding through S
Charge on CO?
neutral
When is [NCS]- intermediate or soft?
intermediate if bonding through N, soft if bonding through S
When is [NCS]- intermediate or soft?
intermediate if bonding through N, soft if bonding through S
What type of ligand is CO?
Pi-acceptor so strong field
What are some bidentate ligands?
acetoacetonate (acac), ethandioate, ethylenediamine
how many e- do bidenentate ligands donate?
4e-
how many e- do monodentate e- donate?
2e-
how can carboxylate ligands bind?
either via one or both oxygens
what spin a d e- is Co(III)
low spin d6 and high CFSE
