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CYL 120 (INORGANIC)
Prof. A. K. Ganguli
AKG
Organic :
Prof Nalin Pant
Minor I & II
1+7
J D Singh
AKG 2
(all lectures till from September 19 to October 17, 2012)
MS-709 , TEL : 1511; email : [email protected]
October 18 to Nov 16 : Prof J D Singh
Quiz ( october)
Major Exam : AKG & JDS (inorganic)
A K Ganguli (ashok@chemistry
([email protected]),
iitd ac in) MS
MS-709
709, Tel :1511
1. Transition metal complexes – REVISION of
Nomenclature, Isomerism and valence bond theory 1
2.
CRYSTAL FIELD Theory
7
Magnetic / optical properties of complexes
Structural distortion in metal complexes
3. Introduction to Inorganic Solids
2
Books Recommended
1 James
1.
J
E
E. H
HuHeey
H
Inorganic chemistry
2 F.
2.
FA
A. Cotton
Cotton, G
G. Willkinsion and P.
P L.
L Gaus
Basic Inorganic Chemistry, J. Wiley and sons (1995) – Singapore
3. Shriver and Atkins : Inorganic Chemistry
( my part)
Quiz
(10 marks; 30 min)
Major
(20 marks; 1 hr)
Why Study Inorganic Chemistry??
Intellectual Pursuit
Practical Impact
1. Eight out top ten chemicals are Inorganic. (H2SO4) max tonnage
2. Inorganic Materials
(Semi conductors, Light guides on linear optical materials, super
conductors)
d t ) G
GaAs,
A KT
KTaO3,
O3 LiNbO3,
LiNbO3 YBa2Cu3O7
YB 2C 3O7
Dupont, Monsanto, Dow Chemicals, Hercules, Baeyer,
Unilever – Top
p Chemical Companies
p
ATOMIC ORBITALS
p
s
d
f
Hψ
ψ =Eψ
S h di
Schrodinger,s
equation
ti
Ψ = R(r) Θ(θ, φ)
n = 1, 2, 3, ……….
l = 0 to n-1
Quantum numbers
For n = 1, l = 0
1s sub shell
For n = 2, l = 0, 1
l=0
2s sub shell
l=1
2p sub shell
Ml = -ll tto +l
+l.
example Y−11(θ,Ԅ)=(1/2)(√3/√2π)(sinθ)e−iԄ.
Ml =-1, l = 1
Transition Metal Complexes
Transition Metal?
Elements having partial filled ‘d’ or ‘f’ shell in any of their
commonly occurring oxidation states.
Fe, Co, Ni, Cu, Ag, Au etc
d - block transition metals.
f -block
block (inner) transition metals (Lanthanides and actinides)
Metals,, variable oxidation states,, hard,, high
g melting
g point
p
Transition metal complexes / Coordination Compounds
A central atom, ion surrounded by anions or neutral molecules, which
are Lewis bases and may be monoatomic or polyatomic, neutral or
anionic (ligands) are coordination compounds.
Ligand: Lewis base bonded
(coordinated) to a metal ion in a
coordination compound.
L
L
Lewis acid
M
L
Lewis base
Monodentate, bidentate
L
Coordination compounds
p
on dissolution give
g
rise to complex
p
ions
(complexes)
[Retains the identity in solution]
[Cr(NH3)6]Cl3
Coordination compound
[Cr(NH3)6]3+ + 3ClComplex ion
How Complexes differ from Double salts??
Double salts on dissolution in water lose their identity
Dissolve in water
K+, Al3+, SO2-
K2SO4.Al2(SO4)3.24H2O (Alum)
No complex ion
Complex ions don’t lose their identity on dissolution
Dissolve in water
[Co(NH3)6]Cl3
[Co(NH3)6]3+ + 3ClComplex ion
S. M. Jorgensen (1837 – 1914)
A. Werner
(1866 - 1919)
Synthesized
y
manyy transition
metal complexes
1st Nobel prize in Inorganic chemistry
(1913) : Werner
CoCl3 – NH3 Complexes
compound
Colour
Moles of
AgCl
Werner’s
formula
CoCl3. 6NH3
Yellow
3
[Co(NH3)6]Cl3
CoCl3. 5NH3
Purple
2
[Co(NH3)5Cl]Cl2
CoCl3. 4NH3
Green
1
[Co(NH3)4Cl2]Cl
W
Werner’s
’ main
i Study
St d
Primary Valencies
[Co(NH3)6]Cl3 + 3AgNO3
3AgCl + Co(NH3)63+
Secondary Valencies
Normally fixed for a particular ion and oxidation state.
[Mn(H2O)6]SO4
2+
H2O
H2O
H2O
Mn
Electrostatic interaction
SO42-
H2O
Covalent bond
H2O
H2O
Octahedral complex
Coordination number is 6 (secondary valency)
Mn2+
Central metal ion (lewis acid)
H2O
Ligand (Lewis base)
Types of Ligands
M
Monodentate
d t t ligands
li
d
Donate one pair of electrons to a central metal ion.
e g Cl-, Br-, I-, NH3, H2O
e.g.
Bidentate ligands
They have two donor atoms
Ethylenediamine (en)
H2N – CH2 – CH2 – NH2
M
Di th l glycol
Dimethyl
l l (glyme)
( l
)
CH3O – CH2 – CH2 – OCH3
M
COOM
Oxalate ion (oxalato)
COO-
More Examples
NH2 – CH2 – COO-
Glycinato (gly)
-OOC
bidentate
– CH2 – NH – CH2 – COO-
Iminodiacetato (imda)
tridentate
NH2 – CH2 – CH2 – NH – CH2
Triethylenetetramine (tren)
NH2 – CH2 – CH2 – NH – CH2
tetradentate
-OOC
Ethylenediamine
tetraacetate (edta)
– CH2
CH2 – COON – CH2 – CH2 - N
-OOC
– CH2
hexadentate
CH2 – COO-
Ambidentate Ligands
O
O–N=O
N
O
nitrito
Nitro
SCN-
thiocyanato
NCS
isothiocyanato
Organic Ligands
N
N
2, 2’-Bipyridine (bpy)
N
N
1,10 – Phenanthroline (phen)
Alkyl groups as ligands
CH3 (methyl), CH3CH2 (ethyl), C6H5 (Phenyl)
Macrocyclic ligands
N
N
N
N
Porphyrin
tetradentate
Nomenclature of Transition metal Compounds
A. Writing the name of the complex compound
1 Designation of ligands
1.
(a) Anionic ligands end with ‘o’
NO2nitro,
CNClchloro,
NO3-
cyano
nitrato
(b) Organic ligands retained their names
Pyridine (py) or ethylenediamine (en)
alkyl groups: methyl, phenyl
(c ) Special names
H2O (aqua), NO (nitrosyl), CO (carbonyl), NH3 (ammine)
2. Designation of metal
(a) Cationic and neutral complexes end in the english name
followed by the oxidation state of the metal in brackets.
e.g. nickel(II) or iron(II).
(b) Anionic complexes have the latin name of the metal
ferrate( ) ,
Stannate ( )
C
Cuprate
t (),
A
Argentate
t t ()
3. Numerical prefixes
(a) For two similar ligands di or bis
(b) three similar ligands tri or tris
(c ) four similar ligands tetra or tetrakis etc.
3. Order of listing
The ligands are to be written in alphabetical order (irrespective of
charge)
eg [CoCl2(NH4)]+ Cleg.
dichlorotetraamminecobalt(III) chloride.
wrong
tetraamminedichlorocobalt(III) chloride.
right
A. Writing the formulae of the complex compound
1. First central metal atom , then anionic ligands and then neutral
ligands
(Cl-,NH
NH3)
[Co (NH3)4Cl2]Cl
wrong
[CoCl2(NH3)4]Cl
correct
Examples
1. [Co (NO2)6] Cl3
hexanitro cobalt (III) chloride
2. [Cu(NH3)4]SO4
tetra amminecopper(II)sulphate
3. [CuCl2(py)2]
bis pyrridinedichlorocopper(II)
py
pp ( )
dichloro dipyridine copper (II)
dichloro bis (py
(pyridine)) copper
pp ((II))
4. cis-[Pt(NH3)2Cl2]
cis-diamminedichloroplatinum(II)
Geometry of complexes
C
Cu
(linear)
Coordination No.2
[NC---Ag---CN]
[C (CN)2
[Cu(CN)
CH3----Hg-----CH3
CN
]-
CN
Cu
Cu
Polymeric compound
Coordination no. 4
(large ligands)
(b) Tetra hedral
(a) Square planar
Mainly d8 systems
Cl
2-
Cl
Cl
Pt
Cl
2-
Ni
Cl
Cl
Cl
Cl
Coordination no. 5
L
L
L
L
L
M
L
L
L
M
L
tbp
Sq. pyramidal
L
[Ni (CN)5]2- shows both structures (little energy differenc)
[CuCl5]3+
NbCl5
TBP structure
TBP structure
O2
Fe
Bi l i ll important
Biologically
i
t t molecules
l l
Haemoglobin,
Oxomyoglobin
N
N
N
N
L
Coordination no. 6
ML6 octahedral
complex
M t important
Most
i
t t from
f
d1 to
t d9
L
L
M
L
L
e. g. [Cr(NH3)6]3+ , [Fe(CN)6]3-
L
Higher coordination possible with large cations and small anions
e.g. [ZrF7]3-, TaCl4(PR3)3
[Nd(OH2)9]3+, [ReH9]2-, [Ce(NO3)6]2-
Square
q
antiprism
p
icosahedron
Isomerism
Structural Isomerism
Stereoisomerism
Geometrical
(Same frame work
b t different
but
diff
t spatial
ti l
arrangement of the
ligands)
Optical
(non-superimposable
i
images)
i
)
mirror
Ionization
Hydrate
y
Coordination
Linkage
Pol meri ation
Polymerization
Ligand isomer
Geometrical Isomers (coordination no. 4) A
B
A
B
A
M
M
M
B
A
A
B
B
B
A
trans
cis
tetrahedral
Square planar
All are optically inactive
Cis/ trans isomers can be isolated
Pt
2-
Cl
Cl
NH3
Pt
Cl
Cl
Cl
NH3
E
Excess
NH3
NH3
Cl
I
NH3
NH3
Pt
NH3
NH3
II
Geometrical Isomerism in Octahedral complexes
MA3B3
A
A
B
A
Facial
A
RuCl3(H2O)3
B
MA2B4
B
B
B
B
M
B
B
B
Meridonal
A
A
M
cis
B
Co(NO
( 2)3((NH3)3
B
A
A
A
M
B
M
B
e.g. [Co Cl2(NH3)4] +
trans
B
A
Optical isomerism
Optical isomers differ only in the direction in which they rotate the plane
of the plane polarized light (enantiomers).
-- -- ---- -
α
solution
plane polarized light
Absence of optical activity
(superimposable mirror images)
1. Presence of a mirror plane.
1
plane
2. Presence of a centre of symmetry.
Cl
NH3
Cl
NH3
NH3
M
NH3
NH3
Cl
Trans
+ dextro
- laevo
Cl
M
[CoCl2(NH3)4]+
Optically inactive
NH3
NH3
NH3
Cis
NH2
Cl
Cl
Co
Cl
Co
NH2
NH2
NH2
NH2
NH2
cis
NH2
Non superimposable mirror images.
Cl
NH2
NH2
(Optically active)
trans
Co
Not optically active
NH2
NH2
Cl
Cl
NH2
N
Bonding Concept
(Rationalise structure)
Bonding in coordination compounds
Sidgwick (1927)
¾ Extended the Lewis theory
¾ Sharing of ‘e’ pair donated by an atom (donor).
Effective atomic Number (EAN)
M accepts electron pairs and converted into inert gas configuration.
e.g.
[Co(NO2)6]3-
Co (Z = 27)
Co3+ = 24e
6(NO2)- = 6*2e = 12e
----------------------
TOTAL = 36e Atomic no. of Krypton (Kr)
Chemical Bonding
G N.
G.
N Lewis
L i (1916)
Sharing of e-’s
Bonding between atoms
H
H
C
..
H
H
H
Structure ??
N
H
H
Lewis diagram
C
Concept
t off h
hybridization
b idi ti
Valence bond Theory
(Pauling – Slater, 1930’s)
Li
Linus
Pauling
P li – N.L.
N L (t
(twice)
i )
“ Nature of the chemical bond”
Bond angles ??
Valence bond Theory
(Pauling)
Complexes
1. Metal ion must make available a number of orbitals equal to the
coordination number for accommodating the electrons from the
ligands.
2. Use of the hybrid orbitals by the metal ion.
¾ Maximum & fruitful overlap with ligand orbitals
¾ Directionality
Note: Hybrid orbitals are not s, p or d orbitals but have a mixed character.
Why Hybridisation?
CH4
F
Four
bonds
b d
C
11s2 2
2s2 2p
2 2
Promotion of
one s electron
x
1s2 2s2 2px1 2py1 2py1
Results in three mutually
perpendicular bonds.
pX
H
z
Hy
90
90
H
H
x
But
H
109o
109o
C
CH4 is Tetrahedral
H
H
H
All
HCH are equal
Successes of V. B. T.
1. Simple structure and Magnetic properties are nicely
explained.
l i d
2. Accounts for low spin square planer and high
tetrahedral complex.
3. Low spin inner – orbital and high spin orbital
complexes.
Failures
[Cu(NH3)4]2+
1. Cannot predict 4 – coordination
― square planer or tetrahedral
VB
T
2+
Cu : 3d9
3d
[Zn(NH3)4]2+
(planar)
(tetrahedral)
both to be tetrahedral
4s
4p
3d
4s
4p
sp3
dsp2
But by experiments there is no evidence of unpaired e- in orbital: e. s. r spectroscopy
22. VBT does not predict any distortion in the symmetrical
complexes. [ideal ― octahedra, tetrahedra]
Au Cu(II)
Au,
Cu(II), Ti(III) complexes are distiorted among many more.
more
3 VBT neglects
3.
l t th
the exited
it d states
t t off the
th complexes.
l
―no thermodynamic properties can be predicted
4. It does not explain the colour (spectra) of complexes.
5. Does not explain
p
the temperature
p
variation of magnetic
g
properties of complexes.