The document discusses the history and development of coordination chemistry, centered around the discoveries of Alfred Werner. It describes how Werner established the field through his work in the late 19th century, defining coordination complexes using a molecular orbital model with ligands bonded to a central metal atom in an octahedral geometry. Examples are given of some of Werner's early complexes that helped prove his theory, as well as other important discoveries like the anticancer drug cisplatin and medical imaging agent Cardiolite. Rules for IUPAC nomenclature of coordination complexes are also outlined.

1. 1
Chemistry of the
d-Block Elements
History:
Louis Nicolas Vauquelin
16. Mai 1763 – 14. Nov. 1829
Leopold Gmelin
2. Aug. 1788 – 13. Apr. 1853
Chemistry of the
d-Block Elements
History:
Pd
NH3
NH3
H3N
H3N
Pd
Cl
Cl
Cl
Cl
CoIII
CN
CN
NC
NC
NC
CN
Louis Nicolas Vauquelin
1813
Gmelin
1822

2. 2
Chemistry of the
d-Block Elements
History:
1844: Peyrone’s Chloride
[PtCl2(NH3)2]
1844: Reiset
[PtCl2(NH3)2] !
(isomers are super-important in chemistry!)
-- note! same formula! --
cis- and trans- Platinum Isomers: Serendipity in Chemistry
"Testicular cancer went from a disease that normally killed about
80% of the patients, to one which is close to 95% curable. This is
probably the most exciting development in the treatment of
cancers that we have had in the past 20 years. It is now the
treatment of first choice in ovarian, bladder, and osteogenic
sarcoma [bone] cancers as well."
—Barnett Rosenberg, who led the research group that discovered
cisplatin, commenting on the impact of cisplatin in cancer
chemotherapy
Cisplatin was approved by the
FDA for the treatment of
genitourinary tumors in 1978.
Since then, Michigan State has
collected over $160 million in
royalties from cisplatin and a
related drug, carboplatin, which
was approved by the FDA in 1989
for the treatment of ovarian
cancers.
Pt
NH3
NH3
O
O
O
O
carboplatin
Prof. Barnett Rosenberg, MSU
(Prof. S.J. Lippard, MIT)
Chemistry of the
d-Block Elements
Newest generation:

3. 3
Chemistry of the
d-Block Elements
B. Rosenberg et al. in Nature 1965, 205, 698
Stephen J. Lippard et al. in Nature (1999), 399, 708 - 712
Basis for recognition of cisplatin-modified DNA by high-mobility-group proteins
SUMMARY: The anticancer activity of cis -diamminedichloroplatinum(II) (cisplatin)
arises from its ability to damage DNA, with the major adducts formed being intrastrand
d(GpG) and d(ApG)
Cisplatin acts by cross-linking DNA in several different ways, making it impossible for rapidly dividing cells to
duplicate their DNA for mitosis. The damaged DNA sets off DNA repair mechanisms, which activate apoptosis
when repair proves impossible. The trans-isomer does not have this pharmacological effect.
Barnett Rosenberg, MSU (1926 - )
Chemistry of the
d-Block Elements
B. Rosenberg et al. in Nature 1965, 205, 698
Stephen J. Lippard et al. in Nature (1999), 399, 708 - 712
Basis for recognition of cisplatin-modified DNA by high-mobility-group proteins
SUMMARY: The anticancer activity of cis -diamminedichloroplatinum(II) (cisplatin)
arises from its ability to damage DNA, with the major adducts formed being intrastrand
d(GpG) and d(ApG)
Cisplatin acts by crosslinking DNA in several different ways, making it impossible for rapidly dividing cells to
duplicate their DNA for mitosis. The damaged DNA sets off DNA repair mechanisms, which activate apoptosis
when repair proves impossible. The trans isomer does not have this pharmacological effect.
Stephen J. Lippard, MIT (??? - )

4. 4
Chemistry of the
d-Block Elements
B. Rosenberg et al. in Nature 1965, 205, 698
Stephen J. Lippard et al. in Nature (1999), 399, 708 - 712
Basis for recognition of cisplatin-modified DNA by high-mobility-group proteins
SUMMARY: The anticancer activity of cis -diamminedichloroplatinum(II) (cisplatin)
arises from its ability to damage DNA, with the major adducts formed being intrastrand
d(GpG) and d(ApG)
Cisplatin acts by crosslinking DNA in several different ways, making it impossible for rapidly dividing cells to
duplicate their DNA for mitosis. The damaged DNA sets off DNA repair mechanisms, which activate apoptosis
when repair proves impossible. The trans isomer does not have this pharmacological effect.
Chemistry of the
d-Block Elements
Another success story at the HEART of coordination chemistry:
CardioLite
"Davison realized that fundamental coordination chemistry
would shed light on the chemical characteristics of the element
technetium and that these basic chemical characteristics could be
translated into the rational design of new radiopharmaceuticals,"
Orvig notes in the article. He calls Davison
"one of the fathers of medicinal inorganic chemistry.“
Prof. Chris Orvig, University of British Columbia
taken from SNM advancing molecular imaging
Alan Davison, MIT (??? - )

5. 5
Chemistry of the
d-Block Elements
Another success story at the HEART of coordination chemistry:
Cardiolite
Chemistry of the
d-Block Elements
The d - Block Elements
http://www.chemsoc.org/viselements/pages/pertable_fla.htm

6. 6
The d - Block Elements…my personal favorites
Chemistry of the
d-Block Elements
The d - Block Elements…my personal favorites
Prof. Karl Wieghardt
Max-Planck-Institute
for Bioinorganic Chemistry
Muelheim/Germany
Chemistry of the
d-Block Elements

7. 7
The Werner & Jørgensen Controversy
Chemistry of the
d-Block Elements
Sophus Mads Jørgensen 1837 – 1914
Alfred Werner – Founder of Coordination Chemistry
“Dot” Representation:
Pentachlorophosphorous PCl5
PCl3 • Cl2
Copper(II) Sulfate Pentahydrate
CuSO4 • 5H2O
Copper(II) Acetate Hydrate
Cu(CH3COO)2 • H2O
Hex(a)ammin Cobalt(III) Chloride
CoCl3 • 6NH3
Chemistry of the
d-Block Elements

8. 8
Alfred Werner
Chemistry of the
d-Block Elements
Seite 111 des 17-jährigen(!) Alfred Werner‘s
„Einleitung in die Chemie“ (1883 – 1884)
über die Formulierung des PCl5 als
molecular compound PCl3 • Cl2
Alfred Werner – Founder of Coordination Chemistry
Copper(II) Acetate Hydrate
Cu(CH3COO)2 • H2O
Hex(a)ammin Cobalt(III) Chloride
CoCl3 • 6NH3
Chemistry of the
d-Block Elements

9. 9
Alfred Werner – Founder of Coordination Chemistry
CoIIICl3
• 4NH3violetvioleo
CoIIICl3
• 4NH3greenpraseo
CoIIICl3
• 5NH3redpurpureo
CoIIICl3
• 6NH3yellowluteo
ComplexColorPrefix
Chemistry of the
d-Block Elements
Hex(a)ammin Cobalt(III) Chloride
CoCl3 • 6NH3
Alfred Werner – Founder of Coordination Chemistry
Chemistry of the
d-Block Elements
Alfred Werner‘s Kollektion (8000+ Komplexe!) & die „Katakomben“ an der Universität Zürich

10. 10
Alfred Werner – Founder of Coordination Chemistry
NH3—Cl
Co—NH3—Cl
NH3—NH3—NH3—NH3—Cl
Cl
Co—NH3—Cl
NH3—NH3—NH3—NH3—Cl
Cl
Co—Cl
NH3—NH3—NH3—NH3—Cl
Cl
Co—Cl
NH3—NH3—NH3—Cl
[Co(NH3)6]Cl3
[Co(NH3)5Cl]Cl2
[Co(NH3)4(Cl)2]Cl
[Co(NH3)4(Cl)2]Cl
Jørgensen Werner
2isomers!
Chemistry of the
d-Block Elements
Alfred Werner – Founder of Coordination Chemistry
Chemistry of the
d -Block Elements

11. 11
Alfred Werner – Leitfähigkeit (Kohlrausch’s Prinzip, Konstitution)
Chemistry of the
d-Block Elements
Alfred Werner & Arturo Miolati (1893 – 1896)
Alfred Werner – Isomere (Konfiguration)
Chemistry of the
d-Block Elements

12. 12
Alfred Werner – Founder of Coordination Chemistry
Chemistry of the
d-Block Elements
Alfred Werner – Founder of Coordination Chemistry
Chemistry of the
d-Block Elements

13. 13
A Sidenote: Serendipity in Chemistry
"Testicular cancer went from a disease that normally killed about
80% of the patients, to one which is close to 95% curable. This is
probably the most exciting development in the treatment of
cancers that we have had in the past 20 years. It is now the
treatment of first choice in ovarian, bladder, and osteogenic
sarcoma [bone] cancers as well."
—Barnett Rosenberg, who led the research group that discovered
cisplatin, commenting on the impact of cisplatin in cancer
chemotherapy
Cisplatin was approved by the
FDA for the treatment of
genitourinary tumors in 1978.
Since then, Michigan State has
collected over $160 million in
royalties from cisplatin and a
related drug, carboplatin, which
was approved by the FDA in 1989
for the treatment of ovarian
cancers.
Pt
NH3
NH3
O
O
O
O
carboplatin
Prof. Barnett Rosenberg, MSU
(Prof. S.J. Lippard, MIT)
Chemistry of the
d-Block Elements
First non-carbon containing chiral compound:
Hexol [(Co ((OH)2Co(NH3)4)3](SO4)3, resolved in 1914
with (+)-bromocamphorsulphonate
Co
O
H
OH
H
O
OH
HO
HO
Co
Co
Co
NH3
NH3
H3N
H3N
NH3
NH3H3N
NH3
H3N
NH3
H3N
NH3
O
S
O
O
O
Br
6+
definitive proof of
Alfred Werner’s
octahedron model
-> Synthesis of
optically active
complexes!
Chemistry of the
d-Block Elements

14. 14
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements
Chemistry of the
d-Block Elements
Coordination Chemistry - Nomenclature

15. 15
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements

16. 16
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements

17. 17
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements

18. 18
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements
Coordination Chemistry - Nomenclature
Chemistry of the
d-Block Elements

19. 19
Coordination Chemistry - Nomenclature
IUPAC Rules for complex formula:
• Coordination complex in square brackets,
charge superscripted
[CrIII(NCO)4(NH3)2] − [PtIIBrClI(NO2)(NH3)] −
[PtIVBrClI(NO2)(py)(NH3)]
• Central atom in front of ligands
• Anionic in front of neutral ligands
• Multiple atoms & abbrev. ligands in round brackets
• Oxidation number superscripted @ central atom
looks awkward…
I would
use
(Br)(Cl)(I)…
abbrev: C5H5N
Chemistry of the
d-Block Elements
Coordination Chemistry - Nomenclature
IUPAC Rules for complex name:
Main Difference: ligands first, followed by central atom
strictly follow alphabetical order
Dichloro(thiourea)(triphenylphosphine)platinum(II)
[PtCl2(py)(NH3)] Amminedichloro(pyridine)platinum(II)
• Ligands in alphabetical order in front of central atom/ion
Specification of oxidation number (Roman numerals) of the
central atom (or the charge number in Arabic numerals
after the name of the central atom)
Name of anionic ligands close with “o”, neutral ligands in
round brackets (except: ammine, aqua, carbonyl, nitrosyl)
Chemistry of the
d-Block Elements

20. 20
Coordination Chemistry - Nomenclature
K3[Fe(CN)6] Potassium-hexacyanoferrate(III) or
Potassium-hexacyanoferrate(3-)
(or Tripotassium-hexacyanoferrate)
K2[PtCl4] Potassium-tetrachloroplatinate(II)
Na2[Fe(CO)4] Disodium-tetracarbonylferrate
[Co(H2O)2(NH3)4]Cl3 Tetraammindiaquacobalt(3+)
chloride
Chemistry of the
d-Block Elements
Coordination Chemistry - Nomenclature
[Ni(H2O)(NH3)4]SO4 Tetra(a)mminediaquanickel(II)
sulfate
Na2[OsCl5N] Disodium-pentachloronitrido-
osmate(VI)
[CoCl(NO2)(NH3)4]Cl Tetra(a)mminechloronitrito-
cobalt(III) chloride
[CoCl(NH2)(en)2]NO3 Amidochlorobis(ethylenediamine)
cobalt(III) nitrate
[FeH(CO)3(NO)] Tricarbonylhydridonitrosyliron(?)
[PtCl(NH2CH3)(NH3)]Cl Amminchlorobis(methylamine)
platinum(II) chloride
Chemistry of the
d-Block Elements

21. 21
Coordination Chemistry - Nomenclature
Ru
PPh 3
PPh 3
H
OC
Cl
PPh 3
Co
OH2
NH3
NC
NC
OH2
NH3
Co
NH2
NH2
N
H2
H2
N
H2N
H2N
Ni
CN
CN
NC
NC
CN0 +
I I I
I I
Carbonylchloro-
hydridotris(tri-
phenylphosphine)
ruthenium(II)
Diamminediaqua-
dicyanocobalt(III)
Tris(ethylenediamine)-
cobalt(III) pentacyano-
nickelate(II)
Chemistry of the
d-Block Elements
Coordination Chemistry - Isomers
Pt
NH3
NH3
N
HO
M
NH3
Cl
Ph 3P
Br
CO
NMe3
M
N
N
N
N
N
N
N
H
CH3
CH3
CH3
H
H3C
H
CH2H3C
CH3
CH3
H3C
1
2
3
3
1
2
3
4
5
6
practice…
Priority Rules: …remember Cahn-Ingold-Prelog?
Chemistry of the
d-Block Elements

22. 22
Coordination Chemistry - Isomers
…in four-coordinate square-planar complexes:
cis- & trans-
and chiral isomers in
square planar complexes
chirality (chiral center) can be incorporated ligand
Chemistry of the
d-Block Elements
Coordination Chemistry - Isomers
…in six-coordinate octahedral complexes:
special case of cis- & trans-
isomers:
carboxyl group
trans to tertiary N
carboxyl group
cis to tertiary N
Chemistry of the
d-Block Elements

23. 23
Coordination Chemistry - Isomers
…in six-coordinate octahedral complexes:
in addition to cis- & trans-
and chiral (Chapter 4)
isomers:
fac- and mer-isomers
more obvious with
poly (tri-)dentate
ligands such as:
tacn, tp- (fac)
or terpy (mer)
N
NN
N
N N
tacn terpy
Chemistry of the
d-Block Elements
Coordination Chemistry - Isomers
…in six-coordinate octahedral complexes:
special case of
chirality in en
or tacn complexes:
NH2
NH2
N
N N
tacn, δδδ or λλλ en
Chemistry of the
d-Block Elements

24. 24
Coordination Chemistry - Isomers
Hydrate Isomerism
CrCl3 • 6H2O (dark green, mostly trans-[CrCl2(H2O)4]Cl)
violet [Cr(H2O)6]Cl3
blue-green [CrCl(H2O)5]Cl2 • H2O
dark green [CrCl2(H2O)4]Cl • 2H2O*
yellow-green [CrCl3(H2O)3] in conc. HCl
separationby
cationion
exchange
chromatography
Chemistry of the
d-Block Elements
Coordination Chemistry - Isomers
Ionization Isomerism
[CoCl(NH3)4(H2O)]Br2 and [CoBr2(NH3)4]Cl • H2O
(also hydrate isomers)
[Co(SO4)(NH3)5]NO3 and [Co(NO3)(NH3)5]SO4
[CoCl(NO2)(NH3)4]Cl and [CoCl2(NH3)4]NO2
Chemistry of the
d-Block Elements

25. 25
Coordination Chemistry - Isomers
Coordination Isomerism
[Pt(NH3)4][PtCl4] (Magnus’ green salt)
different metal ions in different oxidation states:
[Co(en)3][Cr(CN)6] and [Cr(en)3][Co(CN)6]
[Pt(NH3)4][PtCl6] and [PtCl2(NH3)4][PtCl4]
Chemistry of the
d-Block Elements
Coordination Chemistry - Isomers
Linkage (ambidentate) Isomerism
intram
olecular!
Philip Coppens
University at
Buffalo (NY)
Chemistry of the
d-Block Elements

26. 26
Coordination Chemistry - Isomers
Linkage (ambidentate) Isomerism
isothiocyanato thiocyanato (1-diphenylphosphine-3-
dimethylaminepropane)palladium(II)
free rotation
large steric effect
Chemistry of the
d-Block Elements
Coordination Chemistry – Coordination Numbers
& Structures
Notes & Blackboard
Chemistry of the
d-Block Elements

27. 27
Coordination Chemistry – Bonding in TM Complexes
Ligand Fields & Ligand Strengths
High-Spin & Low-Spin Complexes
Chemistry of the
d-Block Elements
The Metals s-, p-, and d-Orbitals:
taken from:
Harvey & Porter
“Introduction to Physical Inorganic Chemistry”
Addison-Wesley 1963
electron density
on the axes!
electron density in between the axes!
The five d-orbitals
Chemistry of the
d-Block Elements

28. 28
Approx. dependency of orbital
energy on atomic number
(nuclear charge)Schematic orbital energy diagram
taken from Harvey & Potter “Introduction to Physical
Inorganic Chemistry” Wesley 1963
Chemistry of the
d-Block Elements
- Review -
Remember???
For example: Nickel (1s2)(2s22p6)(3s23p6) (4s2) (3d8)
In complexes: [Ni2+] (1s2)(2s22p6)(3s23p6) (3d8) unpaired electrons!!!
For a 3d electron: Z* = Z – S
Z*= 28 – [18 x (1.00)] – [7 x (o.35)] = 7.55
(1s, 2s, 2p, 3s, 3p) (3d)
The 18 electrons in the 1s, 2s, 2p, 3s, and 3p levels contribute 1.00
each (Rule 3b); the other 7 electrons in 3d contribute 0.35 each,
and the 4s electrons do not contribute (Rule 2).
For a 4s electron: Z* = Z – S
Z* = 28 – [10 x (1.00)] – [16 x (o.85)] – [1 x (0.35)]
(1s, 2s, 2p) (3s, 3p, 3d) (4s)
Z* = 28 – 23.95 = 4.05 The 4s electrons are held
less tightly than the 3d!
All transition metals loose ns electrons more readily
than (n – 1)d electron:
Ti(III): d1, V(III): d2, Mn(II): d5, Mn(III): d4, Mn(IV): d3, Mn(V): d2

29. 29
Coordination Chemistry – Magnetism
Chemistry of the
d-Block Elements
A) Measurement of Susceptibility by Faraday’s Method
B) Measurement of Magnetization with a SQUID Magnetometer
Principle: In an inhomogeneous field a paramagnetic sample
is attracted into the zone with the largest field; a diamagnetic
sample is repulsed.
Coordination Chemistry – paired/unpaired d-electrons & magnetism
Chemistry of the
d-Block Elements
Measurement of Susceptibility by Faraday’s Method
dF = ½ μ0(χ – χmed)grad(H2)dv
Fz = μ0(χ – χmed)vH dH/dz
in vacuum or helium:
Fz = μ0χg m H(dH/dz) + F’
standard with known χg* and m*
χM = χg
* [m* / (Fz* - F’)][Fz – F’)/m] M0

30. 30
Chemistry of the
d-Block Elements
Coordination Chemistry – molecular magnetism
Chemistry of the
d-Block Elements
Coordination Chemistry – molecular magnetism

31. 31
Chemistry of the
d-Block Elements
Coordination Chemistry – molecular magnetism
Coordination Chemistry – Bonding in TM Complexes
Ligand Fields & Ligand Strengths
High-Spin & Low-Spin Complexes
Chemistry of the
d-Block Elements
• Shape and Symmetry of Ligand and Metal Orbitals
• d-Orbital Splitting in Transition Metal Complexes:
1) Nature of the ligand
2) Symmetry of the Complex

32. 32
Chemistry of the
d-Block Elements
Introduction - History
G. N. Lewis
16. Febr. 1901 – 19. Aug. 1994
Nevil Vincent Sidgwick
05. Mai. 1873 – 15. März 1952
Chemistry of the
d-Block Elements
Lewis Acid-Base Concept:
• Formation of Complexes via Ion-Ion and/or Ion-Dipole Forces:
Fe2+ + 4 Cl− [FeCl4]−
ion - ion
δ+ δ−
Fe2+ + 6 H2O [Fe(OH2)6]2+
ion - dipole
e-hole e-pair adduct

33. 33
Chemistry of the
d-Block Elements
Lewis Acid-Base Concept:
• Formation of Complexes via Ion-Ion and/or Ion-Dipole Forces:
Fe2+ + 6 |CN− [Fe(CN)6]4−
ion - ion
Why not just 5 CN- ?
3d64s04p0 + 6 x 2 3d104s24p6 : 18 e- Krypton e-configuration
same with Fe(CO)5 but plenty of exceptions to the rule
K3[Fe(CN)6] (17e), [FeCl4]− (13e), ...
Chemistry of the
d-Block Elements
Linus Pauling
16. Febr. 1901 – 19. Aug. 1994
Valence-Bond Theory
in Chemistry (1954)
"for his research into the nature of the chemical bond and its application to the
elucidation of the structure of complex substances"
Nobel Peace Price (1962)
only individual in history to have won
two unshared Nobel Prizes

34. 34
Chemistry of the
d-Block Elements
Valence-Bond Theory
Chemistry of the
d-Block Elements
Shortcomings of the Valence-Bond Theory
1) Fails to predict magnetic properties (unpaired electrons)
e.g.: i) all Co(III) Complexes are diamagnetic; except [CoF6]3-, [CoF3(H2O)3]
ii) Cr(III) in Oh: 3 unpaired e−; Cr(II) in Oh: predicted: 2e−, exp.: 4 unpaired e−
2) Ni(II) planar vs. octahedral is supposed to introduce change from covalent to ionic
e.g.: [Ni(en)2]2+ 2NH3 [Ni(NH3)2(en)2]
3) Two Atomic Orbitals (AOs) produce MO(bonding) and MO(antibonding)
4) Color of Transition Metal Complexes! E.g.: [Ti(H2O)6]3+ λmax = 490 nm

35. 35
Chemistry of the
d-Block Elements
Crystal Field Theory
Hans Bethe (PhD in theor. physics)
2. Juli 06 – 06. März 05 ;=)
Electrostatic Model:
M+ + L− [M—L]
Underlying Principles:
♦ Ligand-Field Strength
♦ Asymmetric part of the electron interaction
♦ Spin-Orbit Splitting
Chemistry of the
d-Block Elements
σ - Symmetrical Metal-Ligand Interaction:
taken from: Harvey & Porter “Introduction to Physical Inorganic Chemistry” Addison-Wesley 1963
Note Symmetry of Orbitals!
s = g
p = u
d = g
f = u

36. 36
Chemistry of the
d-Block Elements
Shortcomings of the Crystal-Field Theory
1) Ligands are not negatively charged hard spheres
2) Many complexes with significantly covalent bonds
Chemistry of the
d-Block Elements
Molecular Orbital Theory
Friedrich Hund
04. Febr. 1896 – 31. März 1997

37. 37
Chemistry of the
d-Block Elements
Molecular Orbital Theory
Erich Hückel
1896 - 1980
Robert S. Mulliken
1896 - 1986
Chemistry of the
d-Block Elements
Molecular Orbital Theory
1) Considers IONIC as well as COVALENT bonding
2) Here: No Mathmatical but Phenomenological Considerations
3) MO Theory Contains Aspects of Valence-Bond (VB-) and Crystal-Field Theory
Molecular Orbitals (MOs) are formed via
Linar Combination of Atomic Orbitals (AOs)
metal center
orbital basis:
5 x nd - orbitals
1 x (n+1)s - orbital
3 x (n+1)p - orbitals
combines with
ligand
valence orbitals
Can be s, p, or spn

38. 38
Chemistry of the
d-Block Elements
Molecular Orbital Theory
1) Only orbitals with same symmetry interact (e.g.: M=O or M≡O?)
2) For optimal interaction, energy difference should not be too large
(e.g.: H-H, H-Cl, NaCl)
3) The better the overlap, the better the orbital combination ( see 2. and distance)
Chemistry of the
d-Block Elements
Molecular Orbital Theory
taken from Riedel „Moderne Anorganische Chemie“ 2. Auflage
six σ-orbitals arranged for an
octahedral complex (σ-Interactions only)
not covered in this lecture…
try at home!

39. 39
Chemistry of the
d-Block Elements
MO Theory
CF
VB
How is Δo (in σ-complexes)
explained in terms of
MO-Theory?
metal d-
orbitals ligand
orbitals
MO Diagram
for octhaedral (Oh)
σ−only complexes
Chemistry of the
d-Block Elements
Molecular Orbital Theory
taken from Cotton, Wilkinson, Gaus „Grundlagen der Anorganischen Chemie“, VCH Verlag

40. 40
Chemistry of the
d-Block Elements
Molecular Orbital Theory
taken from Cotton, Wilkinson, Gaus „Grundlagen der Anorganischen Chemie“, VCH Verlag
Chemistry of the
d-Block Elements
Molecular Orbital Theory
large ΔE between M and L orbitals
• weak orbital interaction
• small d-splitting (ligand field Δo)
small ΔE between M and L orbitals
• strong orbital interaction
• large d-splitting (ligand field Δo)
ΔE ΔE
Cl− vs F−
H3N vs H2O
H2O vs H2S

41. 41
Chemistry of the
d-Block Elements
Molecular Orbital Theory
Introduction of metal-ligand
π−Interaction:
Chemistry of the
d-Block Elements
Molecular Orbital Theory
full σ-donor
orbital
empty π-acceptor
orbital
full σ-donor
orbital
full π-donor
orbital
Stabilization
Destabilization

42. 42
Chemistry of the
d-Block Elements
Molecular Orbital Theory
Interpretation of the Spectrochemical Series in Terms of MO Theory
weak ligands strong ligands
high-spin complexes low-spin complexes
strong π-donor< weak π-donor < pure σ-donor < weak π-acceptor < strong π-acceptor
I− < Br− < S2− < SCN− < Cl− < NO3
− < F−< OH− <
H2O < NCS− < CH3CN < NH3 < en < bpy < phen <
NO2
− < CN− < PR3 < CO
Chemistry of the
d-Block Elements
H2, alkanesDonation of electrons from filled d-orbitals of
metal to empty σ*-orbitals of ligand
dπ—σ*
CO, RNC,
pyridine, CN-, N2,
NO2
-, ethylene
Donation of electrons from filled d-orbitals of
metal to empty π* (antibonding)-orbitals of
ligand
dπ—π*
R2S (R3P, R3As)Donation of electrons from filled d-orbitals of
metal to empty d-orbitals of ligand
dπ—dπ
RO-, RS-, F-, Cl-,
R2N-
Donation of electrons from filled p-orbitals of
ligand to empty d-orbitals of metal
pπ—dπ
Ligand examplesDescriptionType

43. 43
Molecular - Orbital Diagram
for Octahedral Complexes (σ - only)
Chemistry of the
d-Block Elements
Chemistry of the
d-Block Elements

44. 44
Chemistry of the
d-Block Elements
Geometry (Symmetry) Dependence of Ligand—Field Splitting (cont’d):

45. 45
Geometry (Symmetry) Dependence of Ligand—Field Splitting (cont’d):
A Case Study: The Electronic Structure of Hemoglobin/Myoglobin:
A Case Study: The Electronic Structure of Hemoglobin/Myoglobin:
N
N
N
Observation: Diamagnetic Spin Ground State for the Oxy-Form
of Hemoglobin/Myoglobin!
…with FeIII (S = 1/2 or 5/2) and 3O2 (S = 1)???

46. 46
Observation: Diamagnetic Spin Ground State for the Oxy-Form!
A Case Study: The Electronic Structure of Hemoglobin/Myoglobin:
Solution A:
Observation: Diamagnetic Spin Ground State for the Oxy-Form!
A Case Study: The Electronic Structure of Hemoglobin/Myoglobin:

47. 47
Solution B:
Observation: Diamagnetic Spin Ground State for the Oxy-Form!
A Case Study: The Electronic Structure of Hemoglobin/Myoglobin: