Transcript Complexes_naming(download)

Transition metal
chemistry
Coordination compounds – ligands and things
Coordinate covalent bonds and ligands
Nomenclature
Isomerism
Spectroscopy
Electronic structure
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Coordinate covalent bond
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Lewis acid/base chemistry
Lone pair on water (base)
Vacancy on Fe2+ (acid)
Positive, neutral, negative
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The complex can be an
ion that forms part of a
neutral compound square brackets
delineate the complex
Or may exist as a
standalone neutral
compound (no square
brackets)
NiNH  
2
3 6
FeCN 6 
3
Pt NH 3 2 Cl2
Things to consider
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Coordination number – the number of ligands
around the central ion
Geometry – the shape of the complex
Much greater variety and complexity
compared with the geometry of covalent
molecules of the representative elements
Examples of complexes with
different coordination numbers
Coordination
number
2
3
4
5
6
7
8
Complex
[Ag(NH3)2]+, [CuCl2][HgI3]-
[Zn(NH3)4]2+,
[Ni(CN)4]2[Ni(CN)5]-, Fe(CO)5
[Cr(H2O)6]3+,
[Fe(CN)6]3[ZrF7]3[Mo(CN)8]4-
Geometry - prelude
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Rules for determining geometry are more involved than the
simple VSEPR approach that works well with covalent
compounds
Note: same composition may adopt different geometries
Will be dealt with using ligand-field theory
Things to know
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Overall
charge
Writing the correct formula
M Lm X n 
( M  ) ( n )
Square
bracket
Number of
neutral ligands
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Number
of anion
ligands
Determining oxidation state on the central
atom
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Complex charge - Sum of anion charges = o.s.
Ligands – entities with teeth
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Must contain a lone electron pair
Classify the ligands according to the number
of available pairs
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Monodentate – one pair
Bidentate – two pairs
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Polydentate – many pairs
Common ligands and names in
complex
ions
Anion
Name
Neutral
Name
ligand
ligand
Bromide
Bromo
Ammonia
Ammine
Carbonate
Carbonato
Water
Aqua
Chloride
Chloro
Carbon
monoxide
Carbonyl
Cyanide
Cyano
Ethylene
diamine
Ethylene diamine
Fluoride
Fluoro
Hydroxide
Hydroxo
Oxalate
Oxalato
Thiocyanate
Thiocyanato/Iso
thiocyanato
Chelating – ligands with claws
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Ligands with greater than one lone pair can form
more than one bond to a single metal ion
Ethylene diamine (en)– tridentate
EDTA - hexadentate
Important biological entities
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(a) The structure of the porphine molecule. Loss of the two NH protons
gives a planar, tetradentate 2– ligand that can bond to a metal cation. The
porphyrins are derivatives of porphine in which the peripheral H atoms are
replaced by various substituent groups. (b) Schematic of the planar heme
group, the attached protein chain, and the bound O2 molecule in
oxyhemoglobin and oxymyoglobin. The Fe(II) ion has a six-coordinate,
octahedral environment, and the O2 acts as a monodentate ligand.
What’s in a name
Rules, rules, rules
1.
If the compound is a salt, naming is as for
common salts: cation first and then anion
Potassium hexacyanoferrate(III)
K 3 FeCN 6 
Complex ion or neutral complex
2.
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Ligands first then metal
Endings are the thing
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Anionic ligands end in –o
-ide → -o; -ate → -ato
Neutral ligands have normal names except…
H2O (aqua), NH3 (ammine), CO (carbonyl)
One word: nospacebetweenligandandmetal
Diamminedichloroplatinum(II)
Pt NH 3 2 Cl2
More than one ligand
3.
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Indicate number of ligands by prefixes: di-,
tri-, etc.
Ligands are listed in alphabetical order
Tetraaquadichlorochromium(III) chloride
CrH 2O4 Cl2 Cl
It’s all Greek to me
4.
If the ligand name contains a Greek prefix
(ethylenediamine), the ligand name is in
parantheses and use an alternative prefix: bis(2), tris-(3), tetrakis(4)
Tris(ethylenediamine)cobalt(III) chloride
Coen3 Cl3
Roman numerals
5.
Roman numeral in parantheses to indicate
oxidation state of metal in situation where
the o.s. is variable
-ate crimes
6.
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-ate is the conventional ending for the metal in an
anionic complex
Check table for exact wording
Metal
Anion
Name
Metal
Anion
Name
Aluminium
Aluminate
Iron
Ferrate
Chromium
Chromate
Manganese
Manganate
Cobalt
Cobaltate
Nickel
Nickelate
Copper
Cuprate
Platinum
Platinate
Gold
Aurate
Zinc
Zincate