d block part B

Question 1

What assumptions are made for crystal feild theory (2)

Answer 1

1. Metal centres and ligands represented as point charges.

2. Bonding arises through electrostatic interactions between these charges

Question 2

Which D orbitals are directly on the axis

Answer 2

dz2

dx2-y2

Question 3

Which D orbitals are between the axes

Answer 3

dxy
dxz
dyz

Question 4

Explain which d orbitals are destabilised in an octahedral complex

Answer 4

dx2-y2 & dz2

Orbitals point directly towards ligands on xyz axes. electrons in orbitals and ligands repel each other, E increases

Question 5

Explain which D orbitals re more stable in an octahedreal complex

Answer 5

dxy, xz, yz
Orbitals point inbetween xyz axes, electrons in orbitals and ligands electronically relieved by not pointing directly towards each other.

Question 6

what is a crystal field theory

Answer 6

the predicting of the splitting on d-orbitals into two or more sets of orbitals at different energies in complexes.

Question 7

describe the 2 new energy sets in CFT

Answer 7

Eg - upper energy set with 2 orbitals

t2g - lower energy with 3 orbitals.

Question 8

what is crystal field stabilisation energy?

CFSE

Answer 8

stabilisation of particular arrangements of ligands with respect to spherical ligand field (barycentre)

Question 9

What is CFSE equation

Answer 9

[(-2/5 x num electrons in t2g) + (+3/5 x num elecrons in eg)]Delta oct + zP

Question 10

How are magnetic properties determined?

Answer 10

no unpaired e = diamagnetic

at least 1 unpaired e = paramagnetic.

Question 11

What are high spin and low spin complex arrangements when do they occur?

Answer 11

High spin: more unpaired electrons, weak field, when DeltaOct is small.
Low spin: Fewer unpaired electrons, strong field, When DeltaOct is large

Question 12

How to determine High or low spin?

Answer 12

High spin when DeltaOct< pairing energy

Low spin DeltaOct >pairing energy

Question 13

Whats special about d8, 9 and 10 central metals

Answer 13

High and low spins don’t exist,

d10 and d5 CFSE is 0

Question 14

How does DeltaOct change with oxidation state?

Answer 14

DeltaOct increases with OS as pulls ligands closer as increased effective nuclear charge, larger electrostatic repulsions between electrons in orbitals and ligands, more d splitting

Question 15

How Does DeltaOct change down group?

Answer 15

Increases, Larger d orbitals, better contact with ligands, more interactions, more destabilising.
Larger orbitals pairing energy decreases more room for electrons less repulsion.

Question 16

All 2nd and 3rd row octahedral TM complexes are _________

Answer 16

low spin

Question 17

Order ligands examples from high spin to low spin increases delta size

Answer 17

Halide donor < O donor < N donor < C donor

Question 18

Order increasing delta size with respect to pi interactions

Answer 18

Strong pi DONOR < weak pi donor < no pi donor < weak pi acceptor < strong pi acceptor
(weak sigma –> strong sigma)

Question 19

Which is the orbital arrangement in the tetrahedral complex?

Answer 19

No d orbitals point directly towards ligands as ligands slightly above and below plane.

Question 20

Which orbitals are more stable in the tetrahedral complex, why?

Answer 20

Dx2-y2 and dz2, point less towards ligands more stable so E is lowered

Question 21

Which orbitals are less stable in the tetrahedral complex, why?

Answer 21

Dxy, xz, yz as point more towards ligands, repulsion destabilises complex, E raised.

Question 22

Describe the energy sets for orbitals in tetrahedral ligand feild

Answer 22

Higher: t2 3 orbitals xy xz and yz
lower: e z2 and x2-y2

Question 23

CFSEtet equation

Answer 23

[(−3/5 xno. electrons in e)+(+2/5 x no. electrons in t2)]DeltaTet+zP

Question 24

How to D orbitals order in energy for Square planar complex?

Answer 24

Dx2-y2»> dxy > dz2 > dxz=dyz

Question 25

What factors determine is 4 coordination is square planar or tetrahedral?

Answer 25

Square planar:
First row of TMs with strong field ligands - larger d orbital spitting allowed more electrons at lower energy.

2nd / 3rd row TMs are S.P. larger D orbitals, more repulsive interations with ligands larger d splitting,

Question 26

What is the Jahn-Teller effect

Answer 26

Systems will remove the degeneracy and undergo distortion to remove the ambiguity of which orbital single electron will occupy.

Question 27

Which systems does Jahn-Teller effect usually take place?

Answer 27

Mostly octahedral complexes with odd number of electrons occupying eg set. example d9, high spin d4 or low spin d7

Question 28

Describe orbitals energy for Z elongation Jahn-Teller

Answer 28

Equatorial plane compresses. Z orbitals more stable and so z2 , dxz and dyz will lower in E. lone electron in x2-y2

Question 29

Describe orbitals energy for Z compression Jahn-Teller

Answer 29

More z orbitals interaction, destabilised, z2, dxz and dyz increase in E. lone electron in z2