1. The document discusses transition metal complexes, including their properties and bonding models. 2. Key topics covered include ligand field theory, isomerism in complexes, naming complexes using IUPAC rules, and the electronic spectra and magnetic properties used to evaluate bonding models. 3. Several bonding models are mentioned, including Werner's theory, Sidgwick's theory, crystal field theory, and ligand field theory.

1. V.SANTHANAM
DEPARTMENT OF CHEMISTRY
SCSVMV

2. V. SANTHANAM

3. V. SANTHANAM

4.  e- in partially filled d sublevel absorbs visible light
 moves to slightly higher energy d orbital
Magnetic properties due to unpaired electrons
V. SANTHANAM

5.  Consist of a complex ion and necessary counter ions
[Co(NH3)5Cl]Cl2
 Complex ion: [Co(NH3)5Cl]2+
Co3+ + 5 NH3 + Cl-
1(3+) + 5 (0) + 1(1-)
2+
 Counter ions: 2 Cl-
V. SANTHANAM

6.  Transition metals act as Lewis acids
 Form complexes/complex ions
Fe3+(aq) + 6CN-(aq)  Fe(CN)6
3-(aq)
Ni2+(aq) + 6NH3(aq)  Ni(NH3)6
2+(aq)
Lewis acid Lewis base Complex
ion
Lewis acid Lewis base Complex
ion
V. SANTHANAM

7. Complex contains central metal ion
bonded to one or more molecules or
anions
Lewis acid = metal = center of
coordination
Lewis base = ligand = molecules/ions
covalently bonded to metal in
complex
V. SANTHANAM

8. Complex ion remains intact upon dissolution in water
[Co(NH3)6]Cl3 [Pt(NH3)4]Br2
V. SANTHANAM

9.  Species where transition metal ion is
surrounded by a certain number of ligands.
 Transition metal ion: Lewis acid
 Ligands: Lewis
bases
 Co(NH3)6
3+
 Pt(NH3)3Br+
V. SANTHANAM

10.  Molecule or ion having a lone electron pair
that can be used to form a bond to a metal
ion
 (Lewis base).
 coordinate covalent bond: metal-ligand
bond
 monodentate: one bond to metal ion
 bidentate: two bond to metal ion
 polydentate: more than two bonds
to a metal ion
possible
V. SANTHANAM

11. V. SANTHANAM

12. V. SANTHANAM

13.  1. Cation then anion
 2. Total charges must balance to zero
 3. Complex ion in brackets
 K2[Co(NH3)2Cl4]
 [Co(NH3)4Cl2]Cl
V. SANTHANAM

14.  1. Cation then anion
 2. Ligands
 in alphabetical order before metal
ion
 neutral: molecule name*
 anionic: -ide  -o
 prefix indicates number of each
 3. Oxidation state of metal ion in () only if
more than one possible
 4. If complex ion = anion, metal ending  -ate
V. SANTHANAM

15. V. SANTHANAM

16. V. SANTHANAM

17.  K2[Co(NH3)2Cl4]
potassium
diamminetetrachlorocobaltate(II)
 [Co(NH3)4Cl2]Cl
tetraamminedichlorocobalt(III) chloride
V. SANTHANAM

18. V. SANTHANAM

19. V. SANTHANAM

20. 20_441
Isomers
(same formula but different properties)
Stereoisomers
(same bonds, different
spatial arrangements)
Structural
isomers
(different bonds)
Optical
isomerism
Geometric
(cis-trans)
isomerism
Linkage
isomerism
Coordination
isomerism
V. SANTHANAM

21.  Coordination isomerism
 Composition of the complex ion varies.
 [Cr(NH3)5SO4]Br
 and [Cr(NH3)5Br]SO4
V. SANTHANAM

22.  Ligand isomerism:
 Same complex ion structure but point of
attachment of at least one of the ligands differs.
 [Co(NH3)4(NO2)Cl]Cl
 and [Co(NH3)4(ONO)Cl]Cl
V. SANTHANAM

23. [Co(NH3)5(NO2)]Cl2
Pentaamminenitrocobalt(III)
chloride
[Co(NH3)5(ONO)]Cl2
Pentaamminenitritocobalt(III)
chloride
V. SANTHANAM

24.  Geometric isomerism (cis-trans):
 Atoms or groups arranged differently
spatially relative to metal ion
[Pt(NH3)2Cl2]
V. SANTHANAM

25. V. SANTHANAM

26. 20_444
H3N
Co
H3N
NH3
NH3
Cl
Cl
H3N
Co
H3N
NH3
Cl
Cl
NH3
Cl
Cl
Co
Cl
Cl
Co
(a) (b)
V. SANTHANAM

27.  Optical isomerism:
 Have opposite effects on plane-polarized light
 (no superimposable mirror images)
20_446
Unpolarized
light
Polarizing
filter
Polarized
light
Tube
containing
sample

Rotated
polarized light
V. SANTHANAM

28. 20_448
Left hand
Right hand
Mirror image
of right hand
V. SANTHANAM

29. V. SANTHANAM

30. 20_449
N
N
N
N
N
N
Co
N
N
N
N
N
N
Co
Mirror image
of Isomer I
Isomer I Isomer II
N
N
N
N
N
N
Co
V. SANTHANAM

31. 20_450
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Cl
Cl
N
N
N
N
Co
Isomer IIIsomer I
cistrans
Isomer II cannot be
superimposed exactly
on isomer I. They are
not identical structures.
The trans isomer and
its mirror image are
identical. They are not
isomers of each other.
Isomer II has the same
structure as the mirror
image of isomer I.(b)(a)
V. SANTHANAM

32.  Models for the bonding in transition
metal complexes must be consistent with
observed behavior.
 Specific data used include stability (or
formation) constants, magnetic
susceptibility, and the electronic (UV/Vis)
spectra of the complexes.
V. SANTHANAM

33. Werner’s Theory
Sidgwick’s Theory
Crystal Field Theory
Ligand Field Theory
V. SANTHANAM

34. V. SANTHANAM

35.  Valence Bond theory provides the
hybridization for octahedral complexes.
 For the first row transition metals, the
hybridization can be: d2sp3 (using the 3d, 4s
and 4p orbitals), or sp3d2 (using the 4s, 4p
and 4d orbitals).
.
V. SANTHANAM

36. V. SANTHANAM

37. V. SANTHANAM

38. V. SANTHANAM

39. V. SANTHANAM

40.  The valence bond approach isn’t used
because it fails to explain the electronic
spectra and magnetic moments of most
complexes
V. SANTHANAM