D And F Block Elements

Front 1

When do metals in compounds not have the same oxidation state?

Back 1

When they are in gas phase,

e.g. Cr is d5s1 in gas phase not d6 as it is in a complex

Front 2

Define oxidation state

Back 2

The charge remaining on a central metal atom when all ligands are removed in their closed shell configurations

Front 3

What are the steps for assigning oxidation state to a metal in a complex? E.g. [MnO4]-

Back 3

Assigned charge contributes: -1

Remove 4O ligands: +8 (2x4)

Overall charge = +7

Oxidation state of Mn = +7

Front 4

Distinguish between an X, L, and Z ligand

Back 4

An X ligand donates one electron to the metal

An L ligand donates lone pair to form a two electron dative covalent bond

Z ligands accept 2 electrons from the metal to form a two electron dative coordinate covalent bond

Front 5

Define the electron number (E.N)

Back 5

Number of valence electrons on M+

Plus the number of e- from ligands

Front 6

Define the L.N.

(ligand number?)

Back 6

Number of electrons used by ligand in binding to the metal

Front 7

What is [MX6]- equivalent to?

Back 7

[MLX5]

Front 8

What is [MX6]+ equivalent to?

Back 8

[MZX5]

Front 9

What is [ML6]- equivalent to?

Back 9

[ML6X]

Front 10

What is [ML6]+ equivalent to?

Back 10

[ML5X]

Front 11

Find the E.N. of [Fe(CN6)]3-

Back 11

[Fe(CN6)]3- = [MX6]3-

= [MX3L3]

Number of electrons on Fe = 8

Number of electrons from X = 3

Number electrons from L = 3x2

Total = 17

Front 12

Find the E.N. of [NH4]+

Back 12

[NH4]+ = [MX4]+ = [MX3Z]

= 5 + 3 + 0 = 8

Front 13

Give two examples of a didentate ligands and name their classes

Back 13

Ethylendiamine (en) = L2

Oxalate (ox) = X2

Front 14

_

X2 - What is it?

Back 14

Monodentate ligands that behave as X2

E.g. =O, =S

Front 15

What is equivalent to _

X2 -?

Back 15

_

X2 - = X

Front 16

What is the electron number of [CO3]2-?

Back 16

_ _

[MX6]2- = [MX2X2]

= 4 + 2 + 2 = 8

Front 17

What do you call a loss of x?

Back 17

Reductive elimination

Front 18

What do you call a loss of L?

Back 18

L-elimination

Front 19

What do you call a loss of L followed by the addition of X?

Back 19

Oxidative replacement

Front 20

What do you call a loss of 2X and addition of L?

Back 20

Replacement elimination

Front 21

What do you call a gain of 2X and loss of L?

Back 21

Replacement addition

Front 22

Loss of x gain of L

Back 22

reductive replacement

Front 23

Addition of L

Back 23

L addition

Front 24

Addition of X

Back 24

Oxidative addition

Front 25

What are the first row of the f-block called?

Back 25

Lanthanoids

Front 26

What are the second row of the f-block called?

Back 26

Actinoides

Front 27

Which are the only 3 elements in the f block that use 5d orbitals

Back 27

La, Ce, Gd

Front 28

Explain why most of the lactinoids are the same size but Yb and Eu are bigger

Back 28

Most of the metals can be considered as M3+ ions floating in a sea of electrons, consisting of 3 electrons per metal.

Eu and Yb can be considered as M2+ ions in a sea of electrons with 2 electrons per metal atom. Less bonding means a larger radius

Front 29

Explain why 4f electrons are barely exposed to external influences such as ligands

Back 29

4f radial distribution function has no nodes.

The bulk of the electron density is therefore very close to the nucleus and hence very tightly held, they are core.

Front 30

Why do 4f electrons not screen 5d and 6s electrons very well?

Back 30

Because 5d and 6s orbitals have inner lobes inside the 4f orbitals.

Imperfect screening.

Front 31

Why are Lu and La similar size?

Back 31

La has the electron configuration 6s25d1

Lu has the electron configuration 6s24f75d1

f electrons are core and do not increase the size of Lu, also due to imperfect screening do not shield the d electron from the nucleus

Front 32

What is the most common lanthanoid oxidation state?

Back 32

Ln(III)

Front 33

Why are lanthanoid ionization energies very similar?

Back 33

Imperfect screening

Front 34

What electrons are generally lost first for Ln(III)?

Back 34

6s2 and d

Front 35

Why are f-block not involved in covalent interactions

Back 35

They are core and too small to interact with ligands

Ln-L bonding largely ionic

Front 36

Name the f orbitals

Back 36

In order of highest energy first

fx^3, fy^3, fz^3 (degenerate)

fx(z^2 - y^2), fy(z^2 - x^2), fz(x^2-y^2)(degenerate)

fxyz

Front 37

What orientation are the f orbital cubic set?

Back 37

Point along axes

Front 38

What is the most common coordination geometry for f-block elements?

Back 38

Octahedral, although in crystals can get 8 or 9 coordination number

Front 39

Most d-block complexes are symmetric, why are some not?

Back 39

Jahn-Teller distortions

Front 40

If you have a d9 complex, what will the Jahn Teller distortion be if the last electron goes into the dz^2 orbital making it double degenerate?

Back 40

Tetragonal elongation. Axial bonds elongate and equatorial compress

Front 41

What happens in a square planar CF splitting diagram?

Back 41

Dxy promoted above dz^2

Front 42

What is the hybridization of an octahedral hybrid?

Back 42

d2sp3

Leaves 3 d orbitals as non-bonding (the t2g set)

Front 43

Why does backbonding occur with CO ligands?

Back 43

Electrons from non-bonding metal t2g set backbond with empty pi* orbitals

Front 44

Describe the interactions of CO ligands with metals

Back 44

CO is a sigma electron donor, and a pi electron acceptor due to backbonding

Front 45

Why are CO and Halides contrasting ligands?

Back 45

CO accepts pi electrons via backbonding

Halides donate pi electrons using p orbitals

Front 46

Why does delta oct decrease for metal - halide complexes?

But increase for Metal - CO complexes?

Back 46

For halides the T2g set decrease in energy decreasing the splitting, for CO ligands the electrons are going into the antibonding orbital so increase in energy causing a larger split

Front 47

What is the 18 electron rule?

Back 47

The number of valence electrons on the central metal atom + the number of electrons provided by the attached ligands equal the number of electrons possessed by the next noble gas

Front 48

Why is the electron rule obeyed?

Back 48

For ligands such as CO and CN-, once the 18 electron rule has been achieved, the next available orbitals are high lying and antibonding.

Many exceptions to the rule, mainly weak crystal field splitters

Front 49

Why can ligands that are strong sigma donors and have a strong pi effect only have 18 electrons?

(e.g. CO)

Back 49

Large delta oct, meaning that t2g are low in energy can be regarded as bonding orbitals

Leaves 9 orbitals available for bonding = 18 electrons

Front 50

Why can ligands that are weak sigma donors and have a weak pi effect have a range of 12-22 electrons?

(e.g. F, OH2, Cl)

Back 50

very small delta oct; 6 orbitals available for bonding, with t2g non-bonding and eg very weakly antibonding.

Electrons can fill t2g and also eg as the additional energy of forming extra M-L bonds can provide the energy needed to overcome the antibonding

Front 51

Why can ligands that are strong sigma donors and have a weak pi effect have 12-18 electrons?

(e.g. NCS)

Back 51

Larger delta oct gap than weak, weak, smaller then strong strong, means that electrons can go into non-bonding t2g but not into antibonding eg

Front 52

How many valence electrons are there for

[Mn(CO)5]2 ?

Back 52

Mn(0) = d7

CO = (5x2) = 10

Mn ligands contribute 1 each in bond = 1

Total = 18

Front 53

What is a metal cluster?

Back 53

A species with three or more metals linked by M-M bonds

Front 54

What kind of bond does Re2 form?

Back 54

An Re-Re quadruple bond

Front 55

Explain why the Cl atoms in [Re2Cl8]2- are eclipsed

Back 55

There is dsp2 hybridization using the s, px, py and dx^2-y^2 orbitals.

The remaning pz orbital forms a dp hybrid with the dz^2 orbital.

The dp hybrids form a sigma bond between the Re atoms.

The dxz orbitals forms a pi bond between the Re, as do the dyz giving a triple bond.

The dxy are unable to match their symmetry to form a pi bond, so form a delta bond where they bond directly above and below each other. This gives a quadruple bond consisting of one sigma, 2 pi and one delta bond, overcomes the energy of eclipsed Cl

Front 56

What are the requirements for an M-M quadruple bond

Back 56

2 metal centres and 8 electrons. E.g. metals that have d4 electrons;

[ReCl4]2 (2-) = (Re+3)

[MoCl4]2 (4-) = (Mo+2)

Front 57

Which compounds can act as pseudo halides?

Back 57

PR3 and SCN but make molecule more neutral

Front 58

What is delta oct?

Back 58

Ligands approach a metal ion in opposite directions, e.g the five d orbitals. Leads to different repulsions and eg and t2g set. Delta oct is the difference between these two

Front 59

What increases delta oct?

Back 59

Higher oxidation or stronger ligand