CHEM1112 Lecture Notes - Lecture 25: Transition Metal, Ammonia, Oxidation State
19 May 2018
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Work out the oxidation state of a transition metal in a complex
Oxidation state of transition metal ion = charge on complex - sum of charges on the ligands
e.g. oxidation state of transition metal ions in these complexes
Na3[FeCl6]
a)
Since Na3, this means overall charge on the complex is 3-
Each of the Cl- ligands has a 1- charge
Fe + (6x-1) = -3
Fe = -3 +6 = 3+
Therefore oxidation state of Fe is III
Make sure to remove counterions!!!
[CoCl(NH3)5]Cl2
b)
Removing the 2 Cl- counterions -> complex has 2+ charge
NH3 is neutral and Cl- = 1- charge
So -1 + Co = 2+ -> Co = 3+
Therefore oxidation state of Co is III
Oxidation state
25.1
Thursday, 2 November 2017
9:29 AM
25. Coordination chemistry Page 1
Work out the number of d electrons on a transition metal cation and
the number of unpaired electrons
Transition metals/d-block metals
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Screen clipping taken: 2/11/2017 11:54 PM
In the 4th row
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There is one 4s orbital - can accommodate 2 e-
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5 x 3d orbitals - each can accommodate 2 e- = total of 10 e-
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4s filled first then 3d, as it is lower energy
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Screen clipping taken: 2/11/2017 11:58 PM
Group numbers indicate number of valence e-
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Electronic configurations are given by: [Ar](4s)x(3d)y, where x + y = group
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e.g. Sc (group 3) so [Ar](4s)2(3d)1
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Electronic configurations
ONLY 3d FILLED
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Group number is number of valence e-
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Cation e- = group no. - oxidation no.
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e.g. Ni3+: in group 10, oxidation number is 3
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For cations…
25.2
Thursday, 2 November 2017
9:30 AM
25. Coordination chemistry Page 2
Document Summary
Work out the oxidation state of a transition metal in a complex. Oxidation state of transition metal ion = charge on complex - sum of charges on the ligands a) e. g. oxidation state of transition metal ions in these complexes. Since na3, this means overall charge on the complex is 3- Each of the cl- ligands has a 1- charge. Removing the 2 cl- counterions -> complex has 2+ charge. Nh3 is neutral and cl- = 1- charge. Therefore oxidation state of co is iii: coordination chemistry page 1. Work out the number of d electrons on a transition metal cation and the number of unpaired electrons. There is one 4s orbital - can accommodate 2 e- 5 x 3d orbitals - each can accommodate 2 e- = total of 10 e- 4s filled first then 3d, as it is lower energy. Electronic configurations are given by: [ar](4s)x(3d)y, where x + y = group e. g. sc (group 3) so [ar](4s)2(3d)1.
