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1 | 4905-4908 | On the other hand, [MnCl6]
3–, [FeF6]
3– and [CoF6-]
3– are outer orbital
complexes involving sp
3d
2
hybridisation and are paramagnetic
corresponding to four, five and four unpaired electrons Rationalised 2023-24
131
Coordination Compounds
The spin only magnetic moment of [MnBr4]
2– is 5 9 BM Predict the
geometry of the complex ion |
1 | 4906-4909 | Rationalised 2023-24
131
Coordination Compounds
The spin only magnetic moment of [MnBr4]
2– is 5 9 BM Predict the
geometry of the complex ion Since the coordination number of Mn
2+ ion in the complex ion is 4, it
will be either tetrahedral (sp
3 hybridisation) or square planar (dsp
2
hybridisation) |
1 | 4907-4910 | 9 BM Predict the
geometry of the complex ion Since the coordination number of Mn
2+ ion in the complex ion is 4, it
will be either tetrahedral (sp
3 hybridisation) or square planar (dsp
2
hybridisation) But the fact that the magnetic moment of the complex
ion is 5 |
1 | 4908-4911 | Predict the
geometry of the complex ion Since the coordination number of Mn
2+ ion in the complex ion is 4, it
will be either tetrahedral (sp
3 hybridisation) or square planar (dsp
2
hybridisation) But the fact that the magnetic moment of the complex
ion is 5 9 BM, it should be tetrahedral in shape rather than square
planar because of the presence of five unpaired electrons in the d orbitals |
1 | 4909-4912 | Since the coordination number of Mn
2+ ion in the complex ion is 4, it
will be either tetrahedral (sp
3 hybridisation) or square planar (dsp
2
hybridisation) But the fact that the magnetic moment of the complex
ion is 5 9 BM, it should be tetrahedral in shape rather than square
planar because of the presence of five unpaired electrons in the d orbitals Example 5 |
1 | 4910-4913 | But the fact that the magnetic moment of the complex
ion is 5 9 BM, it should be tetrahedral in shape rather than square
planar because of the presence of five unpaired electrons in the d orbitals Example 5 7
Example 5 |
1 | 4911-4914 | 9 BM, it should be tetrahedral in shape rather than square
planar because of the presence of five unpaired electrons in the d orbitals Example 5 7
Example 5 7
Example 5 |
1 | 4912-4915 | Example 5 7
Example 5 7
Example 5 7
Example 5 |
1 | 4913-4916 | 7
Example 5 7
Example 5 7
Example 5 7
Example 5 |
1 | 4914-4917 | 7
Example 5 7
Example 5 7
Example 5 7
Solution
Solution
Solution
Solution
Solution
5 |
1 | 4915-4918 | 7
Example 5 7
Example 5 7
Solution
Solution
Solution
Solution
Solution
5 5 |
1 | 4916-4919 | 7
Example 5 7
Solution
Solution
Solution
Solution
Solution
5 5 3 Limitations
of Valence
Bond
Theory
5 |
1 | 4917-4920 | 7
Solution
Solution
Solution
Solution
Solution
5 5 3 Limitations
of Valence
Bond
Theory
5 5 |
1 | 4918-4921 | 5 3 Limitations
of Valence
Bond
Theory
5 5 4 Crystal
Field
Theory
While the VB theory, to a larger extent, explains the formation, structures
and magnetic behaviour of coordination compounds, it suffers from
the following shortcomings:
(i) It involves a number of assumptions |
1 | 4919-4922 | 3 Limitations
of Valence
Bond
Theory
5 5 4 Crystal
Field
Theory
While the VB theory, to a larger extent, explains the formation, structures
and magnetic behaviour of coordination compounds, it suffers from
the following shortcomings:
(i) It involves a number of assumptions (ii) It does not give quantitative interpretation of magnetic data |
1 | 4920-4923 | 5 4 Crystal
Field
Theory
While the VB theory, to a larger extent, explains the formation, structures
and magnetic behaviour of coordination compounds, it suffers from
the following shortcomings:
(i) It involves a number of assumptions (ii) It does not give quantitative interpretation of magnetic data (iii) It does not explain the colour exhibited by coordination compounds |
1 | 4921-4924 | 4 Crystal
Field
Theory
While the VB theory, to a larger extent, explains the formation, structures
and magnetic behaviour of coordination compounds, it suffers from
the following shortcomings:
(i) It involves a number of assumptions (ii) It does not give quantitative interpretation of magnetic data (iii) It does not explain the colour exhibited by coordination compounds (iv) It does not give a quantitative interpretation of the thermodynamic
or kinetic stabilities of coordination compounds |
1 | 4922-4925 | (ii) It does not give quantitative interpretation of magnetic data (iii) It does not explain the colour exhibited by coordination compounds (iv) It does not give a quantitative interpretation of the thermodynamic
or kinetic stabilities of coordination compounds (v) It does not make exact predictions regarding the tetrahedral and
square planar structures of 4-coordinate complexes |
1 | 4923-4926 | (iii) It does not explain the colour exhibited by coordination compounds (iv) It does not give a quantitative interpretation of the thermodynamic
or kinetic stabilities of coordination compounds (v) It does not make exact predictions regarding the tetrahedral and
square planar structures of 4-coordinate complexes (vi) It does not distinguish between weak and strong ligands |
1 | 4924-4927 | (iv) It does not give a quantitative interpretation of the thermodynamic
or kinetic stabilities of coordination compounds (v) It does not make exact predictions regarding the tetrahedral and
square planar structures of 4-coordinate complexes (vi) It does not distinguish between weak and strong ligands The crystal field theory (CFT) is an electrostatic model which considers
the metal-ligand bond to be ionic arising purely from electrostatic
interactions between the metal ion and the ligand |
1 | 4925-4928 | (v) It does not make exact predictions regarding the tetrahedral and
square planar structures of 4-coordinate complexes (vi) It does not distinguish between weak and strong ligands The crystal field theory (CFT) is an electrostatic model which considers
the metal-ligand bond to be ionic arising purely from electrostatic
interactions between the metal ion and the ligand Ligands are treated
as point charges in case of anions or point dipoles in case of neutral
molecules |
1 | 4926-4929 | (vi) It does not distinguish between weak and strong ligands The crystal field theory (CFT) is an electrostatic model which considers
the metal-ligand bond to be ionic arising purely from electrostatic
interactions between the metal ion and the ligand Ligands are treated
as point charges in case of anions or point dipoles in case of neutral
molecules The five d orbitals in an isolated gaseous metal atom/ion
have same energy, i |
1 | 4927-4930 | The crystal field theory (CFT) is an electrostatic model which considers
the metal-ligand bond to be ionic arising purely from electrostatic
interactions between the metal ion and the ligand Ligands are treated
as point charges in case of anions or point dipoles in case of neutral
molecules The five d orbitals in an isolated gaseous metal atom/ion
have same energy, i e |
1 | 4928-4931 | Ligands are treated
as point charges in case of anions or point dipoles in case of neutral
molecules The five d orbitals in an isolated gaseous metal atom/ion
have same energy, i e , they are degenerate |
1 | 4929-4932 | The five d orbitals in an isolated gaseous metal atom/ion
have same energy, i e , they are degenerate This degeneracy is
maintained if a spherically symmetrical field of negative charges
surrounds the metal atom/ion |
1 | 4930-4933 | e , they are degenerate This degeneracy is
maintained if a spherically symmetrical field of negative charges
surrounds the metal atom/ion However, when this negative field is
due to ligands (either anions or the negative ends of dipolar molecules
like NH3 and H2O) in a complex, it becomes asymmetrical and the
degeneracy of the d orbitals is lifted |
1 | 4931-4934 | , they are degenerate This degeneracy is
maintained if a spherically symmetrical field of negative charges
surrounds the metal atom/ion However, when this negative field is
due to ligands (either anions or the negative ends of dipolar molecules
like NH3 and H2O) in a complex, it becomes asymmetrical and the
degeneracy of the d orbitals is lifted It results in splitting of the d
orbitals |
1 | 4932-4935 | This degeneracy is
maintained if a spherically symmetrical field of negative charges
surrounds the metal atom/ion However, when this negative field is
due to ligands (either anions or the negative ends of dipolar molecules
like NH3 and H2O) in a complex, it becomes asymmetrical and the
degeneracy of the d orbitals is lifted It results in splitting of the d
orbitals The pattern of splitting depends upon the nature of the crystal
field |
1 | 4933-4936 | However, when this negative field is
due to ligands (either anions or the negative ends of dipolar molecules
like NH3 and H2O) in a complex, it becomes asymmetrical and the
degeneracy of the d orbitals is lifted It results in splitting of the d
orbitals The pattern of splitting depends upon the nature of the crystal
field Let us explain this splitting in different crystal fields |
1 | 4934-4937 | It results in splitting of the d
orbitals The pattern of splitting depends upon the nature of the crystal
field Let us explain this splitting in different crystal fields ( a ) Crystal field splitting in octahedral coordination entities
In an octahedral coordination entity with six ligands surrounding
the metal atom/ion, there will be repulsion between the electrons in
metal d orbitals and the electrons (or negative charges) of the ligands |
1 | 4935-4938 | The pattern of splitting depends upon the nature of the crystal
field Let us explain this splitting in different crystal fields ( a ) Crystal field splitting in octahedral coordination entities
In an octahedral coordination entity with six ligands surrounding
the metal atom/ion, there will be repulsion between the electrons in
metal d orbitals and the electrons (or negative charges) of the ligands Such a repulsion is more when the metal d orbital is directed towards
the ligand than when it is away from the ligand |
1 | 4936-4939 | Let us explain this splitting in different crystal fields ( a ) Crystal field splitting in octahedral coordination entities
In an octahedral coordination entity with six ligands surrounding
the metal atom/ion, there will be repulsion between the electrons in
metal d orbitals and the electrons (or negative charges) of the ligands Such a repulsion is more when the metal d orbital is directed towards
the ligand than when it is away from the ligand Thus, the
2
2
x
y
d
and
dz2
orbitals which point towards the axes along the direction of
the ligand will experience more repulsion and will be raised in
energy; and the dxy, dyz and dxz orbitals which are directed between
the axes will be lowered in energy relative to the average energy in
the spherical crystal field |
1 | 4937-4940 | ( a ) Crystal field splitting in octahedral coordination entities
In an octahedral coordination entity with six ligands surrounding
the metal atom/ion, there will be repulsion between the electrons in
metal d orbitals and the electrons (or negative charges) of the ligands Such a repulsion is more when the metal d orbital is directed towards
the ligand than when it is away from the ligand Thus, the
2
2
x
y
d
and
dz2
orbitals which point towards the axes along the direction of
the ligand will experience more repulsion and will be raised in
energy; and the dxy, dyz and dxz orbitals which are directed between
the axes will be lowered in energy relative to the average energy in
the spherical crystal field Thus, the degeneracy of the d orbitals
has been removed due to ligand electron-metal electron repulsions
in the octahedral complex to yield three orbitals of lower energy, t2g
set and two orbitals of higher energy, eg set |
1 | 4938-4941 | Such a repulsion is more when the metal d orbital is directed towards
the ligand than when it is away from the ligand Thus, the
2
2
x
y
d
and
dz2
orbitals which point towards the axes along the direction of
the ligand will experience more repulsion and will be raised in
energy; and the dxy, dyz and dxz orbitals which are directed between
the axes will be lowered in energy relative to the average energy in
the spherical crystal field Thus, the degeneracy of the d orbitals
has been removed due to ligand electron-metal electron repulsions
in the octahedral complex to yield three orbitals of lower energy, t2g
set and two orbitals of higher energy, eg set This splitting of the
Rationalised 2023-24
132
Chemistry
degenerate levels due to the
presence of ligands in a
definite geometry is termed as
crystal field splitting and
the energy separation is
denoted by Do (the subscript
o is for octahedral) (Fig |
1 | 4939-4942 | Thus, the
2
2
x
y
d
and
dz2
orbitals which point towards the axes along the direction of
the ligand will experience more repulsion and will be raised in
energy; and the dxy, dyz and dxz orbitals which are directed between
the axes will be lowered in energy relative to the average energy in
the spherical crystal field Thus, the degeneracy of the d orbitals
has been removed due to ligand electron-metal electron repulsions
in the octahedral complex to yield three orbitals of lower energy, t2g
set and two orbitals of higher energy, eg set This splitting of the
Rationalised 2023-24
132
Chemistry
degenerate levels due to the
presence of ligands in a
definite geometry is termed as
crystal field splitting and
the energy separation is
denoted by Do (the subscript
o is for octahedral) (Fig 5 |
1 | 4940-4943 | Thus, the degeneracy of the d orbitals
has been removed due to ligand electron-metal electron repulsions
in the octahedral complex to yield three orbitals of lower energy, t2g
set and two orbitals of higher energy, eg set This splitting of the
Rationalised 2023-24
132
Chemistry
degenerate levels due to the
presence of ligands in a
definite geometry is termed as
crystal field splitting and
the energy separation is
denoted by Do (the subscript
o is for octahedral) (Fig 5 8) |
1 | 4941-4944 | This splitting of the
Rationalised 2023-24
132
Chemistry
degenerate levels due to the
presence of ligands in a
definite geometry is termed as
crystal field splitting and
the energy separation is
denoted by Do (the subscript
o is for octahedral) (Fig 5 8) Thus, the energy of the two eg
orbitals will increase by (3/5)
Do and that of the three t2g will
decrease by (2/5)Do |
1 | 4942-4945 | 5 8) Thus, the energy of the two eg
orbitals will increase by (3/5)
Do and that of the three t2g will
decrease by (2/5)Do The crystal field splitting,
Do, depends upon the field
produced by the ligand and
charge on the metal ion |
1 | 4943-4946 | 8) Thus, the energy of the two eg
orbitals will increase by (3/5)
Do and that of the three t2g will
decrease by (2/5)Do The crystal field splitting,
Do, depends upon the field
produced by the ligand and
charge on the metal ion Some
ligands are able to produce
strong fields in which case, the
splitting will be large whereas
others produce weak fields
and consequently result in
small splitting of d orbitals |
1 | 4944-4947 | Thus, the energy of the two eg
orbitals will increase by (3/5)
Do and that of the three t2g will
decrease by (2/5)Do The crystal field splitting,
Do, depends upon the field
produced by the ligand and
charge on the metal ion Some
ligands are able to produce
strong fields in which case, the
splitting will be large whereas
others produce weak fields
and consequently result in
small splitting of d orbitals In general, ligands can be arranged in a series in the order of increasing
field strength as given below:
I
– < Br
– < SCN
– < Cl
– < S
2– < F
– < OH
– < C2O4
2– < H2O < NCS
–
< edta
4– < NH3 < en < CN
– < CO
Such a series is termed as spectrochemical series |
1 | 4945-4948 | The crystal field splitting,
Do, depends upon the field
produced by the ligand and
charge on the metal ion Some
ligands are able to produce
strong fields in which case, the
splitting will be large whereas
others produce weak fields
and consequently result in
small splitting of d orbitals In general, ligands can be arranged in a series in the order of increasing
field strength as given below:
I
– < Br
– < SCN
– < Cl
– < S
2– < F
– < OH
– < C2O4
2– < H2O < NCS
–
< edta
4– < NH3 < en < CN
– < CO
Such a series is termed as spectrochemical series It is an
experimentally determined series based on the absorption of light
by complexes with different ligands |
1 | 4946-4949 | Some
ligands are able to produce
strong fields in which case, the
splitting will be large whereas
others produce weak fields
and consequently result in
small splitting of d orbitals In general, ligands can be arranged in a series in the order of increasing
field strength as given below:
I
– < Br
– < SCN
– < Cl
– < S
2– < F
– < OH
– < C2O4
2– < H2O < NCS
–
< edta
4– < NH3 < en < CN
– < CO
Such a series is termed as spectrochemical series It is an
experimentally determined series based on the absorption of light
by complexes with different ligands Let us assign electrons in the d
orbitals of metal ion in octahedral coordination entities |
1 | 4947-4950 | In general, ligands can be arranged in a series in the order of increasing
field strength as given below:
I
– < Br
– < SCN
– < Cl
– < S
2– < F
– < OH
– < C2O4
2– < H2O < NCS
–
< edta
4– < NH3 < en < CN
– < CO
Such a series is termed as spectrochemical series It is an
experimentally determined series based on the absorption of light
by complexes with different ligands Let us assign electrons in the d
orbitals of metal ion in octahedral coordination entities Obviously,
dthe single d electron occupies one of the lower energy t2g orbitals |
1 | 4948-4951 | It is an
experimentally determined series based on the absorption of light
by complexes with different ligands Let us assign electrons in the d
orbitals of metal ion in octahedral coordination entities Obviously,
dthe single d electron occupies one of the lower energy t2g orbitals In
2 and d
3 coordination entities, the d electrons occupy the t2g orbitals
singly in accordance with the Hund’s rule |
1 | 4949-4952 | Let us assign electrons in the d
orbitals of metal ion in octahedral coordination entities Obviously,
dthe single d electron occupies one of the lower energy t2g orbitals In
2 and d
3 coordination entities, the d electrons occupy the t2g orbitals
singly in accordance with the Hund’s rule For d
4 ions, two possible
patterns of electron distribution arise: (i) the fourth electron could
either enter the t2g level and pair with an existing electron, or (ii) it
could avoid paying the price of the pairing energy by occupying the
eg level |
1 | 4950-4953 | Obviously,
dthe single d electron occupies one of the lower energy t2g orbitals In
2 and d
3 coordination entities, the d electrons occupy the t2g orbitals
singly in accordance with the Hund’s rule For d
4 ions, two possible
patterns of electron distribution arise: (i) the fourth electron could
either enter the t2g level and pair with an existing electron, or (ii) it
could avoid paying the price of the pairing energy by occupying the
eg level Which of these possibilities occurs, depends on the relative
magnitude of the crystal field splitting, Do and the pairing energy, P
(P represents the energy required for electron pairing in a single
orbital) |
1 | 4951-4954 | In
2 and d
3 coordination entities, the d electrons occupy the t2g orbitals
singly in accordance with the Hund’s rule For d
4 ions, two possible
patterns of electron distribution arise: (i) the fourth electron could
either enter the t2g level and pair with an existing electron, or (ii) it
could avoid paying the price of the pairing energy by occupying the
eg level Which of these possibilities occurs, depends on the relative
magnitude of the crystal field splitting, Do and the pairing energy, P
(P represents the energy required for electron pairing in a single
orbital) The two options are:
(i) If Do < P, the fourth electron enters one of the eg orbitals giving the
configuration
3
1
2g
g
t
e |
1 | 4952-4955 | For d
4 ions, two possible
patterns of electron distribution arise: (i) the fourth electron could
either enter the t2g level and pair with an existing electron, or (ii) it
could avoid paying the price of the pairing energy by occupying the
eg level Which of these possibilities occurs, depends on the relative
magnitude of the crystal field splitting, Do and the pairing energy, P
(P represents the energy required for electron pairing in a single
orbital) The two options are:
(i) If Do < P, the fourth electron enters one of the eg orbitals giving the
configuration
3
1
2g
g
t
e Ligands for which Do < P are known as weak
field ligands and form high spin complexes |
1 | 4953-4956 | Which of these possibilities occurs, depends on the relative
magnitude of the crystal field splitting, Do and the pairing energy, P
(P represents the energy required for electron pairing in a single
orbital) The two options are:
(i) If Do < P, the fourth electron enters one of the eg orbitals giving the
configuration
3
1
2g
g
t
e Ligands for which Do < P are known as weak
field ligands and form high spin complexes (ii) If Do > P, it becomes more energetically favourable for the fourth
electron to occupy a t2g orbital with configuration t2g
4eg
0 |
1 | 4954-4957 | The two options are:
(i) If Do < P, the fourth electron enters one of the eg orbitals giving the
configuration
3
1
2g
g
t
e Ligands for which Do < P are known as weak
field ligands and form high spin complexes (ii) If Do > P, it becomes more energetically favourable for the fourth
electron to occupy a t2g orbital with configuration t2g
4eg
0 Ligands
which produce this effect are known as strong field ligands and
form low spin complexes |
1 | 4955-4958 | Ligands for which Do < P are known as weak
field ligands and form high spin complexes (ii) If Do > P, it becomes more energetically favourable for the fourth
electron to occupy a t2g orbital with configuration t2g
4eg
0 Ligands
which produce this effect are known as strong field ligands and
form low spin complexes Calculations show that d
4 to d
7 coordination entities are more
stable for strong field as compared to weak field cases |
1 | 4956-4959 | (ii) If Do > P, it becomes more energetically favourable for the fourth
electron to occupy a t2g orbital with configuration t2g
4eg
0 Ligands
which produce this effect are known as strong field ligands and
form low spin complexes Calculations show that d
4 to d
7 coordination entities are more
stable for strong field as compared to weak field cases Fig |
1 | 4957-4960 | Ligands
which produce this effect are known as strong field ligands and
form low spin complexes Calculations show that d
4 to d
7 coordination entities are more
stable for strong field as compared to weak field cases Fig 5 |
1 | 4958-4961 | Calculations show that d
4 to d
7 coordination entities are more
stable for strong field as compared to weak field cases Fig 5 8: d orbital splitting in an octahedral crystal field
Rationalised 2023-24
133
Coordination Compounds
Fig |
1 | 4959-4962 | Fig 5 8: d orbital splitting in an octahedral crystal field
Rationalised 2023-24
133
Coordination Compounds
Fig 5 |
1 | 4960-4963 | 5 8: d orbital splitting in an octahedral crystal field
Rationalised 2023-24
133
Coordination Compounds
Fig 5 9: d orbital splitting in a tetrahedral
crystal field |
1 | 4961-4964 | 8: d orbital splitting in an octahedral crystal field
Rationalised 2023-24
133
Coordination Compounds
Fig 5 9: d orbital splitting in a tetrahedral
crystal field In the previous Unit, we learnt that one of the most distinctive
properties of transition metal complexes is their wide range of colours |
1 | 4962-4965 | 5 9: d orbital splitting in a tetrahedral
crystal field In the previous Unit, we learnt that one of the most distinctive
properties of transition metal complexes is their wide range of colours This means that some of the visible spectrum is being removed from
white light as it passes through the sample, so the light that emerges
is no longer white |
1 | 4963-4966 | 9: d orbital splitting in a tetrahedral
crystal field In the previous Unit, we learnt that one of the most distinctive
properties of transition metal complexes is their wide range of colours This means that some of the visible spectrum is being removed from
white light as it passes through the sample, so the light that emerges
is no longer white The colour of the complex is complementary to
that which is absorbed |
1 | 4964-4967 | In the previous Unit, we learnt that one of the most distinctive
properties of transition metal complexes is their wide range of colours This means that some of the visible spectrum is being removed from
white light as it passes through the sample, so the light that emerges
is no longer white The colour of the complex is complementary to
that which is absorbed The complementary colour is the colour
generated from the wavelength left over; if green light is absorbed by
the complex, it appears red |
1 | 4965-4968 | This means that some of the visible spectrum is being removed from
white light as it passes through the sample, so the light that emerges
is no longer white The colour of the complex is complementary to
that which is absorbed The complementary colour is the colour
generated from the wavelength left over; if green light is absorbed by
the complex, it appears red Table 5 |
1 | 4966-4969 | The colour of the complex is complementary to
that which is absorbed The complementary colour is the colour
generated from the wavelength left over; if green light is absorbed by
the complex, it appears red Table 5 3 gives the relationship of the
different wavelength absorbed and the colour observed |
1 | 4967-4970 | The complementary colour is the colour
generated from the wavelength left over; if green light is absorbed by
the complex, it appears red Table 5 3 gives the relationship of the
different wavelength absorbed and the colour observed 5 |
1 | 4968-4971 | Table 5 3 gives the relationship of the
different wavelength absorbed and the colour observed 5 5 |
1 | 4969-4972 | 3 gives the relationship of the
different wavelength absorbed and the colour observed 5 5 5 Colour in
Coordination
Compounds
Coordinaton
entity
Wavelength of light
absorbed (nm)
Colour of light
absorbed
Colour of coordination
entity
Table 5 |
1 | 4970-4973 | 5 5 5 Colour in
Coordination
Compounds
Coordinaton
entity
Wavelength of light
absorbed (nm)
Colour of light
absorbed
Colour of coordination
entity
Table 5 3: Relationship between the Wavelength of Light absorbed and the
Colour observed in some Coordination Entities
[CoCl(NH3)5]
2+
535
Yellow
Violet
[Co(NH3)5(H2O)]
3+
500
Blue Green
Red
[Co(NH3)6]
3+
475
Blue
Yellow Orange
[Co(CN)6]
3–
310
Ultraviolet
Pale Yellow
[Cu(H2O)4]
2+
600
Red
Blue
[Ti(H2O)6]
3+
498
Blue Green
Violet
The colour in the coordination compounds can be readily explained
in terms of the crystal field theory |
1 | 4971-4974 | 5 5 Colour in
Coordination
Compounds
Coordinaton
entity
Wavelength of light
absorbed (nm)
Colour of light
absorbed
Colour of coordination
entity
Table 5 3: Relationship between the Wavelength of Light absorbed and the
Colour observed in some Coordination Entities
[CoCl(NH3)5]
2+
535
Yellow
Violet
[Co(NH3)5(H2O)]
3+
500
Blue Green
Red
[Co(NH3)6]
3+
475
Blue
Yellow Orange
[Co(CN)6]
3–
310
Ultraviolet
Pale Yellow
[Cu(H2O)4]
2+
600
Red
Blue
[Ti(H2O)6]
3+
498
Blue Green
Violet
The colour in the coordination compounds can be readily explained
in terms of the crystal field theory Consider, for example, the complex
[Ti(H2O)6]
3+, which is violet in colour |
1 | 4972-4975 | 5 Colour in
Coordination
Compounds
Coordinaton
entity
Wavelength of light
absorbed (nm)
Colour of light
absorbed
Colour of coordination
entity
Table 5 3: Relationship between the Wavelength of Light absorbed and the
Colour observed in some Coordination Entities
[CoCl(NH3)5]
2+
535
Yellow
Violet
[Co(NH3)5(H2O)]
3+
500
Blue Green
Red
[Co(NH3)6]
3+
475
Blue
Yellow Orange
[Co(CN)6]
3–
310
Ultraviolet
Pale Yellow
[Cu(H2O)4]
2+
600
Red
Blue
[Ti(H2O)6]
3+
498
Blue Green
Violet
The colour in the coordination compounds can be readily explained
in terms of the crystal field theory Consider, for example, the complex
[Ti(H2O)6]
3+, which is violet in colour This is an octahedral complex
where the single electron (Ti
3+ is a 3d
1 system) in the metal d orbital is
in the t2g level in the ground state of the complex |
1 | 4973-4976 | 3: Relationship between the Wavelength of Light absorbed and the
Colour observed in some Coordination Entities
[CoCl(NH3)5]
2+
535
Yellow
Violet
[Co(NH3)5(H2O)]
3+
500
Blue Green
Red
[Co(NH3)6]
3+
475
Blue
Yellow Orange
[Co(CN)6]
3–
310
Ultraviolet
Pale Yellow
[Cu(H2O)4]
2+
600
Red
Blue
[Ti(H2O)6]
3+
498
Blue Green
Violet
The colour in the coordination compounds can be readily explained
in terms of the crystal field theory Consider, for example, the complex
[Ti(H2O)6]
3+, which is violet in colour This is an octahedral complex
where the single electron (Ti
3+ is a 3d
1 system) in the metal d orbital is
in the t2g level in the ground state of the complex The next higher state
available for the electron is the empty eg level |
1 | 4974-4977 | Consider, for example, the complex
[Ti(H2O)6]
3+, which is violet in colour This is an octahedral complex
where the single electron (Ti
3+ is a 3d
1 system) in the metal d orbital is
in the t2g level in the ground state of the complex The next higher state
available for the electron is the empty eg level If light corresponding to
the energy of blue-green region is absorbed by the complex, it would
excite the electron from t2g level to the eg level (t2g
1eg
0 ® t2g
0eg
1) |
1 | 4975-4978 | This is an octahedral complex
where the single electron (Ti
3+ is a 3d
1 system) in the metal d orbital is
in the t2g level in the ground state of the complex The next higher state
available for the electron is the empty eg level If light corresponding to
the energy of blue-green region is absorbed by the complex, it would
excite the electron from t2g level to the eg level (t2g
1eg
0 ® t2g
0eg
1) Consequently, the complex appears violet in colour (Fig |
1 | 4976-4979 | The next higher state
available for the electron is the empty eg level If light corresponding to
the energy of blue-green region is absorbed by the complex, it would
excite the electron from t2g level to the eg level (t2g
1eg
0 ® t2g
0eg
1) Consequently, the complex appears violet in colour (Fig 5 |
1 | 4977-4980 | If light corresponding to
the energy of blue-green region is absorbed by the complex, it would
excite the electron from t2g level to the eg level (t2g
1eg
0 ® t2g
0eg
1) Consequently, the complex appears violet in colour (Fig 5 10) |
1 | 4978-4981 | Consequently, the complex appears violet in colour (Fig 5 10) The
crystal field theory attributes the colour of the coordination compounds
to d-d transition of the electron |
1 | 4979-4982 | 5 10) The
crystal field theory attributes the colour of the coordination compounds
to d-d transition of the electron ( b ) Crystal field splitting in tetrahedral coordination entities
In tetrahedral coordination entity formation,
the d orbital splitting (Fig |
1 | 4980-4983 | 10) The
crystal field theory attributes the colour of the coordination compounds
to d-d transition of the electron ( b ) Crystal field splitting in tetrahedral coordination entities
In tetrahedral coordination entity formation,
the d orbital splitting (Fig 5 |
1 | 4981-4984 | The
crystal field theory attributes the colour of the coordination compounds
to d-d transition of the electron ( b ) Crystal field splitting in tetrahedral coordination entities
In tetrahedral coordination entity formation,
the d orbital splitting (Fig 5 9) is inverted
and is smaller as compared to the octahedral
field splitting |
1 | 4982-4985 | ( b ) Crystal field splitting in tetrahedral coordination entities
In tetrahedral coordination entity formation,
the d orbital splitting (Fig 5 9) is inverted
and is smaller as compared to the octahedral
field splitting For the same metal, the same
ligands and metal-ligand distances, it can
be shown that Dt = (4/9) D0 |
1 | 4983-4986 | 5 9) is inverted
and is smaller as compared to the octahedral
field splitting For the same metal, the same
ligands and metal-ligand distances, it can
be shown that Dt = (4/9) D0 Consequently,
the orbital splitting energies are not
sufficiently large for forcing pairing and,
therefore, low spin configurations are rarely
observed |
1 | 4984-4987 | 9) is inverted
and is smaller as compared to the octahedral
field splitting For the same metal, the same
ligands and metal-ligand distances, it can
be shown that Dt = (4/9) D0 Consequently,
the orbital splitting energies are not
sufficiently large for forcing pairing and,
therefore, low spin configurations are rarely
observed The ‘g’ subscript is used for the
octahedral and square planar complexes
which have centre of symmetry |
1 | 4985-4988 | For the same metal, the same
ligands and metal-ligand distances, it can
be shown that Dt = (4/9) D0 Consequently,
the orbital splitting energies are not
sufficiently large for forcing pairing and,
therefore, low spin configurations are rarely
observed The ‘g’ subscript is used for the
octahedral and square planar complexes
which have centre of symmetry Since
tetrahedral complexes lack symmetry, ‘g’
subscript is not used with energy levels |
1 | 4986-4989 | Consequently,
the orbital splitting energies are not
sufficiently large for forcing pairing and,
therefore, low spin configurations are rarely
observed The ‘g’ subscript is used for the
octahedral and square planar complexes
which have centre of symmetry Since
tetrahedral complexes lack symmetry, ‘g’
subscript is not used with energy levels Not in visible
region
Rationalised 2023-24
134
Chemistry
It is important to note that
in the absence of ligand,
crystal field splitting does
not occur and hence the
substance is colourless |
1 | 4987-4990 | The ‘g’ subscript is used for the
octahedral and square planar complexes
which have centre of symmetry Since
tetrahedral complexes lack symmetry, ‘g’
subscript is not used with energy levels Not in visible
region
Rationalised 2023-24
134
Chemistry
It is important to note that
in the absence of ligand,
crystal field splitting does
not occur and hence the
substance is colourless For
example, removal of water
from [Ti(H2O)6]Cl3 on heating
renders
it
colourless |
1 | 4988-4991 | Since
tetrahedral complexes lack symmetry, ‘g’
subscript is not used with energy levels Not in visible
region
Rationalised 2023-24
134
Chemistry
It is important to note that
in the absence of ligand,
crystal field splitting does
not occur and hence the
substance is colourless For
example, removal of water
from [Ti(H2O)6]Cl3 on heating
renders
it
colourless Similarly, anhydrous CuSO4
is white, but CuSO4 |
1 | 4989-4992 | Not in visible
region
Rationalised 2023-24
134
Chemistry
It is important to note that
in the absence of ligand,
crystal field splitting does
not occur and hence the
substance is colourless For
example, removal of water
from [Ti(H2O)6]Cl3 on heating
renders
it
colourless Similarly, anhydrous CuSO4
is white, but CuSO4 5H2O is
blue in colour |
1 | 4990-4993 | For
example, removal of water
from [Ti(H2O)6]Cl3 on heating
renders
it
colourless Similarly, anhydrous CuSO4
is white, but CuSO4 5H2O is
blue in colour The influence
of the ligand on the colour
of a complex may be illustrated by considering the [Ni(H2O)6]
2+ complex,
which forms when nickel(II) chloride is dissolved in water |
1 | 4991-4994 | Similarly, anhydrous CuSO4
is white, but CuSO4 5H2O is
blue in colour The influence
of the ligand on the colour
of a complex may be illustrated by considering the [Ni(H2O)6]
2+ complex,
which forms when nickel(II) chloride is dissolved in water If the
didentate ligand, ethane-1,2-diamine(en) is progressively added in the
molar ratios en:Ni, 1:1, 2:1, 3:1, the following series of reactions and
their associated colour changes occur:
[Ni(H2O)6]
2+ (aq)
+ en (aq)
=
[Ni(H2O)4(en)]
2+(aq)
+ 2H2O
green
pale blue
[Ni(H2O)4 (en)]
2+(aq) + en (aq)
=
[Ni(H2O)2(en)2]
2+(aq) + 2H2O
blue/purple
[Ni(H2O)2(en)2]
2+(aq) + en (aq)
=
[Ni(en)3]
2+(aq)
+ 2H2O
violet
This sequence is shown in Fig |
1 | 4992-4995 | 5H2O is
blue in colour The influence
of the ligand on the colour
of a complex may be illustrated by considering the [Ni(H2O)6]
2+ complex,
which forms when nickel(II) chloride is dissolved in water If the
didentate ligand, ethane-1,2-diamine(en) is progressively added in the
molar ratios en:Ni, 1:1, 2:1, 3:1, the following series of reactions and
their associated colour changes occur:
[Ni(H2O)6]
2+ (aq)
+ en (aq)
=
[Ni(H2O)4(en)]
2+(aq)
+ 2H2O
green
pale blue
[Ni(H2O)4 (en)]
2+(aq) + en (aq)
=
[Ni(H2O)2(en)2]
2+(aq) + 2H2O
blue/purple
[Ni(H2O)2(en)2]
2+(aq) + en (aq)
=
[Ni(en)3]
2+(aq)
+ 2H2O
violet
This sequence is shown in Fig 5 |
1 | 4993-4996 | The influence
of the ligand on the colour
of a complex may be illustrated by considering the [Ni(H2O)6]
2+ complex,
which forms when nickel(II) chloride is dissolved in water If the
didentate ligand, ethane-1,2-diamine(en) is progressively added in the
molar ratios en:Ni, 1:1, 2:1, 3:1, the following series of reactions and
their associated colour changes occur:
[Ni(H2O)6]
2+ (aq)
+ en (aq)
=
[Ni(H2O)4(en)]
2+(aq)
+ 2H2O
green
pale blue
[Ni(H2O)4 (en)]
2+(aq) + en (aq)
=
[Ni(H2O)2(en)2]
2+(aq) + 2H2O
blue/purple
[Ni(H2O)2(en)2]
2+(aq) + en (aq)
=
[Ni(en)3]
2+(aq)
+ 2H2O
violet
This sequence is shown in Fig 5 11 |
1 | 4994-4997 | If the
didentate ligand, ethane-1,2-diamine(en) is progressively added in the
molar ratios en:Ni, 1:1, 2:1, 3:1, the following series of reactions and
their associated colour changes occur:
[Ni(H2O)6]
2+ (aq)
+ en (aq)
=
[Ni(H2O)4(en)]
2+(aq)
+ 2H2O
green
pale blue
[Ni(H2O)4 (en)]
2+(aq) + en (aq)
=
[Ni(H2O)2(en)2]
2+(aq) + 2H2O
blue/purple
[Ni(H2O)2(en)2]
2+(aq) + en (aq)
=
[Ni(en)3]
2+(aq)
+ 2H2O
violet
This sequence is shown in Fig 5 11 Fig |
1 | 4995-4998 | 5 11 Fig 5 |
1 | 4996-4999 | 11 Fig 5 11
Aqueous solutions of
complexes of
nickel(II) with an
increasing number
of ethane-1,
2-diamine ligands |
1 | 4997-5000 | Fig 5 11
Aqueous solutions of
complexes of
nickel(II) with an
increasing number
of ethane-1,
2-diamine ligands [Ni(H O) ]
(aq)
2
6
2+
[Ni(H O)
]
(aq)
2
4
en2+
[Ni(H O)
]
(aq)
2
4
2+
en2
[Ni(en) ]
(aq)
3
2+
Colour of Some Gem Stones
The colours produced by electronic transitions within the d orbitals of a
transition metal ion occur frequently in everyday life |
1 | 4998-5001 | 5 11
Aqueous solutions of
complexes of
nickel(II) with an
increasing number
of ethane-1,
2-diamine ligands [Ni(H O) ]
(aq)
2
6
2+
[Ni(H O)
]
(aq)
2
4
en2+
[Ni(H O)
]
(aq)
2
4
2+
en2
[Ni(en) ]
(aq)
3
2+
Colour of Some Gem Stones
The colours produced by electronic transitions within the d orbitals of a
transition metal ion occur frequently in everyday life Ruby [Fig |
1 | 4999-5002 | 11
Aqueous solutions of
complexes of
nickel(II) with an
increasing number
of ethane-1,
2-diamine ligands [Ni(H O) ]
(aq)
2
6
2+
[Ni(H O)
]
(aq)
2
4
en2+
[Ni(H O)
]
(aq)
2
4
2+
en2
[Ni(en) ]
(aq)
3
2+
Colour of Some Gem Stones
The colours produced by electronic transitions within the d orbitals of a
transition metal ion occur frequently in everyday life Ruby [Fig 5 |
1 | 5000-5003 | [Ni(H O) ]
(aq)
2
6
2+
[Ni(H O)
]
(aq)
2
4
en2+
[Ni(H O)
]
(aq)
2
4
2+
en2
[Ni(en) ]
(aq)
3
2+
Colour of Some Gem Stones
The colours produced by electronic transitions within the d orbitals of a
transition metal ion occur frequently in everyday life Ruby [Fig 5 12(a)] is
aluminium oxide (Al2O3) containing about 0 |
1 | 5001-5004 | Ruby [Fig 5 12(a)] is
aluminium oxide (Al2O3) containing about 0 5-1% Cr
3+ ions (d
3), which are
randomly distributed in positions normally occupied by Al
3+ |
1 | 5002-5005 | 5 12(a)] is
aluminium oxide (Al2O3) containing about 0 5-1% Cr
3+ ions (d
3), which are
randomly distributed in positions normally occupied by Al
3+ We may view
these chromium(III) species as octahedral chromium(III) complexes incorporated
into the alumina lattice; d–d transitions at these centres give rise to the colour |
1 | 5003-5006 | 12(a)] is
aluminium oxide (Al2O3) containing about 0 5-1% Cr
3+ ions (d
3), which are
randomly distributed in positions normally occupied by Al
3+ We may view
these chromium(III) species as octahedral chromium(III) complexes incorporated
into the alumina lattice; d–d transitions at these centres give rise to the colour Fig |
1 | 5004-5007 | 5-1% Cr
3+ ions (d
3), which are
randomly distributed in positions normally occupied by Al
3+ We may view
these chromium(III) species as octahedral chromium(III) complexes incorporated
into the alumina lattice; d–d transitions at these centres give rise to the colour Fig 5 |
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