Unless otherwise stated, all images in this file have been reproduced from:
Blackman, Bottle, Schmid, Mocerino and Wille, Chemistry, 2007 (John Wiley)
ISBN: 9 78047081 0866
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e CHEM1002 [Part 3]
Dr Michela SimoneLecturer
BSc (I Hons), MSc, D.Phil. (Oxon), MRSC, MRACI
Weeks 8 – 13
Office Hours: Monday 3-5, Friday 4-5Room: 412A (or 416)
Phone: 93512830e-mail: [email protected]
Slide 3/23
e
Complexes III
• Transition metal atoms of the first transition series have electron configuration [Ar]4sx3dy where x + y is the group number
• For the cations, the electronic configuration is [Ar]3dz where z = group number – oxidation number
• These electrons occupy the ten d-orbitals and, if this leads to unpaired electrons, the complex is paramagnetic
• Complexes in which the 3d orbitals are not empty, half full or full are coloured due to excitations of the electrons
Summary of Last Lecture
Slide 4/23
e
Lecture 15• Metals in Biological Processes• Essential Elements• Toxic Elements• Medicinal Uses• Blackman Chapter 13
Lecture 16• Chemical Kinetics• Rate of Reaction• Rate Laws• Reaction Order• Blackman Chapter 14, Sections 14.1 - 14.3
Complexes IV
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e The Biological Periodic Table
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1HYDROGEN
H1.008
2HELIUM
He4.003
3LITHIUM
Li6.941
4BERYLLIUM
Be9.012
5BORON
B10.81
6CARBON
C12.01
7NITROGEN
N14.01
8OXYGEN
O16.00
9FLUORINE
F19.00
10NEON
Ne20.18
11SODIUM
Na22.99
12MAGNESIUM
Mg24.31
13ALUMINIUM
Al26.98
14SILICON
Si28.09
15PHOSPHORUS
P30.97
16SULFUR
S32.07
17CHLORINE
Cl35.45
18ARGON
Ar39.95
19POTASSIUM
K39.10
20CALCIUM
Ca40.08
21SCANDIUM
Sc44.96
22TITANIUM
Ti47.88
23VANADIUM
V50.94
24CHROMIUM
Cr52.00
25MANGANESE
Mn54.94
26IRON
Fe55.85
27COBALT
Co58.93
28NICKEL
Ni58.69
29COPPER
Cu63.55
30ZINC
Zn65.39
31GALLIUM
Ga69.72
32GERMANIUM
Ge72.59
33ARSENIC
As74.92
34SELENIUM
Se78.96
35BROMINE
Br79.90
36KRYPTON
Kr83.80
37RUBIDIUM
Rb85.47
38STRONTIUM
Sr87.62
39YTTRIUM
Y88.91
40ZIRCONIUM
Zr91.22
41NIOBIUM
Nb92.91
42MOLYBDENUM
Mo95.94
43TECHNETIUM
Tc[98.91]
44RUTHENIUM
Ru101.07
45RHODIUM
Rh102.91
46PALLADIUM
Pd106.4
47SILVER
Ag107.87
48CADMIUM
Cd112.40
49INDIUM
In114.82
50TIN
Sn118.69
51ANTIMONY
Sb121.75
52TELLURIUM
Te127.60
53IODINE
I126.90
54XENON
Xe131.30
55CAESIUM
Cs132.91
56BARIUM
Ba137.34
57-71 72HAFNIUM
Hf178.49
73TANTALUM
Ta180.95
74TUNGSTEN
W183.85
75RHENIUM
Re186.2
76OSMIUM
Os190.2
77IRIDIUM
Ir192.22
78PLATINUM
Pt195.09
79GOLD
Au196.97
80MERCURY
Hg200.59
81THALLIUM
Tl204.37
82LEAD
Pb207.2
83BISMUTH
Bi208.98
84POLONIUM
Po[210.0]
85ASTATINE
At[210.0]
86RADON
Rn[222.0]
87FRANCIUM
Fr[223.0]
88RADIUM
Ra[226.0]
89-103 104RUTHERFORDIUM
Rf[261]
105DUBNIUM
Db[262]
106SEABORGIUM
Sg[266]
107BOHRIUM
Bh[262]
108HASSIUM
Hs[265]
109MEITNERIUM
Mt[266]
LANTHANIDES
57LANTHANUM
La138.91
58CERIUM
Ce140.12
59PRASEODYMIUM
Pr140.91
60NEODYMIUM
Nd144.24
61PROMETHIUM
P.m.[144.9]
62SAMARIUM
Sm150.4
63EUROPIUM
Eu151.96
64GADOLINIUM
Gd157.25
65TERBIUM
Tb158.93
66DYSPROSIUM
Dy162.50
67HOLMIUM
Ho164.93
68ERBIUM
Er167.26
69THULIUM
Tm168.93
70YTTERBIUM
Yb173.04
71LUTETIUM
Lu174.97
ACTINIDES
89ACTINIUM
Ac[227.0]
90THORIUM
Th232.04
91PROTACTINIUM
Pa[231.0]
92URANIUM
U238.03
93NEPTUNIUM
Np[237.0]
94PLUTONIUM
Pu[239.1]
95AMERICIUM
Am[243.1]
96CURIUM
Cm[247.1]
97BERKELLIUM
Bk[247.1]
98CALIFORNIUM
Cf[252.1]
99EINSTEINIUM
Es[252.1]
100FERMIUM
Fm[257.1]
101MENDELEVIUM
Md[256.1]
102NOBELIUM
No[259.1]
103LAWRENCIUM
Lr[260.1]
essential toxic archaeamedicinal
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e Metal Ions in Biology
• Metal ions in biology fall into three groups:
Essential elements e.g. Na+, K+, Mg2+, Ca2+, Fe2+/3+, Cu+/2+, Zn2+
Toxic elements e.g. Pb2+, Hg2+, Be2+
Elements used in medicine e.g. Li+, Pt2+
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eNa+ K+ Mg2+ Ca2+
Ionic radius, Å 1.16 1.52 0.86 1.14
Charge/radius ratio 0.86 0.66 2.32 1.75
Coordination number 6 6-8 6 6-8
Preferred donors O O N,O O
Concentration (mmol/kg)
Intracellular 11 92 2.5 0.1
Extracellular 152 5 1.5 2.5
Seawater 460 10 52 10
Essential Elements
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e Essential Elements - Na+ and K+
Na+, K+ pump
Outer membrane
Inner membrane(inside of the cell)
• Maintaining the Na+ and K+ concentrations requires a pumping system and a lot of energy (ATPase)
Slide 9/23
e Iron – Oxygen Transport/Storage
O
Fe
O
protein
• Oxygen binds reversibly to the free coordination site of Fe
• Square planar coordination of Fe by porphyrin ligand
Slide 10/23
e O2 Transport Complexes
• In humans, transport system (haemoglobin) and storage system (myoglobin) are both Fe(II) complexes:
myoglobin
haemoglobin
muscle lungs
affinity of myoglobin > affinity of haemoglobin
affinity of haemoglobin increases as O2 pressure grows – cooperative effect
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e Haemoglobin and Myoglobin - Structures
• Haemoglobin consists of 4 haem groups, myoglobin consists of 1 haem group:
N
N N
N
Fe2+ Fe2+
HN
N
HN
N
proximal histidine residue
distal histidine residue
Slide 12/23
e Haemoglobin and Myoglobin - Function
Fe3+
HN
N
HN
N
proximal histidine residue
distal histidine residue
OO
weak H-bond?
Fe2+
HN
N
HN
N
proximal histidine residue
distal histidine residue
CO
enforcedbending
partial prevention of (irreversible) CO attachment
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e
HN
N
Fe3+ NN
• Unoxygenated protein contain Fe(II) d6:
• Ion has is too large to fit in haemring and actually sits slightly below it
• Oxygenated protein contains smallerFe(III) d5 which fits into ring
Haemoglobin – Cooperative Effect
proximal histidine residue
OO
Fe2+NN
Fe3+ NN
• The motion of the proximal group is transferred through protein structure to the next deoxygenated haem group decreasing its activation energy for O2 attachment
HN
N
Fe2+NN
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e Carbonic Anhydrase• Zn2+-OH2 is acidic:
N3Zn-OH2 N3Zn-OH + H+
• Metal is bonded to "OH-" which is a good nucleophile
• Binds CO2 reversibly for transfer from muscles to lungs CO2 + OH- CO3
2-
Slide 15/23
e Trace and Toxic Elements
Health
Concentration
Dead
Well
Essential Trace Element
• Lack or shortage of a trace element is damaging to health, as is an excess.
• Low concentrations of toxic metals may be tolerated but at even moderate concentrations they damage health.
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e
Ca5(PO4)3(OH)(s)
• Pb2+ has approximately the same size and charge as Ca2+ - it can substitute for Ca in biological systems especially bone and teeth.
• Many poisons act due to have the same size/charge ratio as an essential molecule/ion
remove as [Pb(EDTA)]2-
Lead in the Body
PbCa4(PO4)3(OH)(s)
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e Pt Anti-Cancer Drugs
Slide 18/23
e Two mice with solid Sarcoma-180 tumors
Untreateddied day 21tumor 3 g.
Bottom mouse treated with cis-[PtCl2(NH3)2] on day 8. Tumor completely regressed by day 14. Died of old age 3 years later.
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e Pt Anti-Cancer Drugs
cis-diamminedichloroplatinum very active
Pt
Cl
NH3
H3N
Cl
PtClH3NClH3N
• All Pt(II) complexes are square planar
trans-diamminedichloroplatinum inactive
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e Pt Anti-Cancer Drugs
• cis-Pt(NH3)2 bonds to two N-bases in the DNA• causes DNa helix to "kink" preventing it from replicating
• trans-Pt(NH3)2 cannot bind to DNA
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e Summary: Biological Periodic Table
Learning Outcomes - you should now be able to:
• Identify essential, toxic and medicinal elements• Explain functioning of metals in body• Relate medicinal uses to function of element• Think about consequences for drug design (for
example: why cis-PtCl2(NH3)2 is active but trans form is not)
Next lecture:
• Reaction kinetics
x
Desferal is taken over 8-12 hour periods up to six times per week.A value of logK = 30.6 is associated with the following equilibrium:
Fe3+ + LH3+ FeL+ + 3H+ where LH3
+ = Desferal
Practice Examples
H3N
N
HN
OH
O
O
N
O
NH
HO
O
NHO
O
Desferal
1. Hemochromatosis or “iron overload” is a potentially fatal disorder in which excess iron is deposited in the bodily organs as insoluble hydrated iron(III) oxide. It can be treated by administration of desferioxamine B (Desferal), a natural substance isolated from fungi.
Briefly describe the chemical basis for the use of Desferal in iron overload therapy.
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x Practice Examples
2. Compounds of d-block elements are frequently paramagnetic. Using the box notation to represent atomic orbitals, account for this property in compounds of Ni2+.
3. Complete the following table.
Formula O.N. CN 3dn Species in water
K3[FeF6]
[Cr(NH3)5(OH2)]Cl3
[Zn(en)Cl2]
en = ethylenediamine = NH2CH2CH2NH2