D-Block Metal Complexes - Spin States & Properties

Front 1

Paramagnetic

Back 1

substance which has one or more unpaired electrons; heavier when weigned in a magnetic field

Front 2

Diamagnetic

Back 2

substance which has no unpaired electrons; unaffected weight in a magnetic field

Front 3

colored d-block metal complexes are paramagnetic or diamagnetic?

Back 3

Paramagnetic. Diamagnetic complexes are colorless.

Front 4

The color of a metal complex depends on

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the bound ligand

Front 5

Crystal field theory

Back 5

describes the effect of ligands on the energies of the metal ion d-orbitals

Front 6

Name and describe the 5 d-orbitals. Which are interaxial and which are axial?

Back 6

Interaxial: d(xy), d(yz), d(xz)
Axial: d(z^2) and d(x^2-y^2)

Front 7

Which orbitals have higher energy, Axial or Interaxial?

Back 7

The 2 axial orbitals have more energy

Front 8

Ligands approach the metal ion axially or interaxially?

Back 8

Axially. The axial orbitals repel the ligand lone pairs of electrons and thus have higher energy.

Front 9

Which orbitals do electrons fill first? Why?

Back 9

The interaxial orbitals are filled first because they are of lower energy

Front 10

Define d-orbital splitting energy.

Back 10

the difference in energy between the axial and interaxial orbitals which is determined by the binding ligand and oxidation state of the metal ion

Front 11

The symbol for d-orbital splitting energy

Back 11

Δ°

Front 12

Spectrochemical series

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the arrangement of ligand strengths which is used to compare splitting energies (large to small)

Front 13

Name several ligands with large Δ° [2]

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CO, CN-

Front 14

Name several ligands with average Δ° [3]

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en, NH3, H2O

Front 15

Name several ligands with small Δ° [3]

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F-, Cl-, Br- (halides)

Front 16

The magnitude of Δ° depends on. [2]

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The ligand strength (determined from the spectrochemical series) and the oxidation state of the metal ion.

Front 17

What is the relationship between Δ° and oxidation state? Why?

Back 17

A higher oxidation state will have a higher Δ°. A higher oxidation state metal ion will have a closer ligand increasing repulsion.

Front 18

Explain the relationship between Δ° and the color of the metal complex?

Back 18

the magnitude of Δ° emitted is usually equal to the region of visible light.

Front 19

What number of electrons in the d-block is there an option for low spin or high spin? Explain.

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4-7 electreons. If less than 4, all will be unpaired (of the same spin) and if more than 7, all interaxial orbitals will already be filled.

Front 20

Discuss the difference between high spin and low spin for d-metal complexes.

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High spin will prefer to place electron unpaired and in the axial orbitals whereas low spin will prefer place electrons paired and in the interaxial orbitals

Front 21

What determines a high or low spin?

Back 21

The value of Δ°. When Δ° is greater than the energy required to pair 2 electrons, a low spin will occur and vice versa

Front 22

High spin

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indicates more unpaired electrons since the Δ° is LESS than the energy required to pair electrons.

Front 23

Low spin

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indicates more paired electrons since the Δ° is MORE than the energy required to pair electrons

Front 24

A d^6 ion (6 electrons) with low spin is paramagnetic or diamagnetic?

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Diamagenitc - 3 pairs of electrons in the interaxial orbitals.

Front 25

A d^6 ion (6 electrons) with high spin is paramagnetic or diamagnetic?

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Paramagnetic - 1 pair of electrons in an interaxial orbital and four unpaired electrons

Front 26

d-d electronic transition

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describes the process of an interaxial electron jumping to an axial orbital (excited) when light is absorbed. only possible for paramagnetic complexes

Front 27

Relate the Jahn-Teller Effect to d-block metal complexes

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The axial bonds correspond to the axial orbital d(z^2) which is repelled outwards making the bonds longer.

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Spectrophotometer

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measures (and plots) the amount of radiation absorbed against the energy/wavelength of radiation in a sample; spectrum is the name of the plot

Front 29

UV-VIS spectrum

Back 29

graph of Absorbance vs. wavelength. associated with the electronic transition accompanying the absorption of UV-visible radiation by a molecule

Front 30

Consider the relationship between Δ°, wavelength and absorbance.

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A larger Δ° will have a corresponding lower wavelength and lower maximum absorbance