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TRANSITION-METAL
COMPLEXES
2017-05-22
prof. V. Paulauskas
1
TRANSITION-METAL COMPLEXES –
are species in which several anions or
neutral molecules, called ligands, bond to a
central transition-metal atom or ion
2017-05-22
prof. V. Paulauskas
2
REACTIONS TO PRODUCE COMPLEXES
Fe(CN)2 + 4KCN  K4[Fe(CN)6]
AlCl3 + 6H2O  [Al(OH2)6]Cl3
Fe + 5CO  [Fe(CO)5]
2017-05-22
prof. V. Paulauskas
3
COMPLEX CONSIST OF:
• Outer sphere
• Inner sphere (complex ion)
0uter sphere
– consist of ions, which are far from central
ion, and are written outside the bracets
example.:
2017-05-22
K+ in complex compound K4[Fe(CN)6]-4
prof. V. Paulauskas
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STRUCTURE OF COMPLEXES
Inner sphere
– is written in the brackets
Complex ion consists of central ion and ligands
example.:
K4[Fe(CN)6]-4
• Metal positive ion or neutral atom is called as complex forming or central
•Anions or neutral molecules which are attached to the central metal ion are
called ligands
• Number of the attached ligands is called coordination number
2017-05-22
prof. V. Paulauskas
5
STRUCTURE OF COMPLEXES
Bonding between central metal ion and ligands is called coordinating
bonding which is of donor-acceptorial origin (Coordination compounds)
Ligands – donors of the electrones (has a pair of electrones)
Metal ion – acceptor of the electrones (has a free electrone orbital)
2D: + A  D
: A
: D (D-A-D)
Ligands
Complexing metal ion
Transition metals are capable of bonding a wide variety of anions
or neutral molecules to form complex ions
2017-05-22
prof. V. Paulauskas
6
STRUCTURE OF COMPLEXES
Complexing – central particle:
• Metal ions (cations): Ag+, Cu2+, Co3+, Pt4+
• Metal neutral atoms: Mn0, Cr0, Fe0, Ni0
• Non-metal ions: B3+, Si4+, P5+
Metal
Naming of metals in complex
anions
2017-05-22
Name
Fe
ferrate
Cu
cuprate
Sn
stanate
Ag
argentate
Au
aurate
prof. V. Paulauskas
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STRUCTURE OF COMPLEXES
Ligands – surround the central particle:
• negative ions (anions): Cl-, CN-, HO-, CO32• small neutral molecules: H2O0, CO0, NH30
• big polar molecules: (CH2)2(NH2)2 ethylendiamine
In latine “ligare”, means to be attached
• Coordinacion number – number of the attached ligands
• Coordination number can vary – 1-12
• The most common – 4 ir 6
2017-05-22
prof. V. Paulauskas
8
STRUCTURE OF COMPLEXES
K4[Fe(CN)6]
1) complex inner sphere – [Fe(CN)6]4 2) central (complexing) particle – Fe2+
3) six attached ligands – (CN)−
4) coordination number – 6
5) complex outer sphere – 4K+
2017-05-22
prof. V. Paulauskas
9
SYSTEMATIC NAMING
Ligand
formula
F-, ClBr-, INO2OHCNSCN2017-05-22
Ligand
formula
Naming
Naming
acetato
cyano
CH3COOCO32H2O (OH2)
NH3
CO
thyocyanato
(CH2)2(NH2)2
ethylendiamine
fluoro, chloro
bromo, iodo
nitro
hydroxo
prof. V. Paulauskas
carbonato
aqua
ammine
carbonyl
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NAMING RULES
1. Name the cation first ant then the anion
As for simple salts: NaCl – potassium chloride
2. Components of Inner sphere are named from right to left
[←]
3. Denote the number of ligands of a particular type by a Greek prefix:
(mono=1, di=2, tri=3, tetra=4, penta=5, hexa=6, etc.)
4. Name the ligands – if there is more than one type of ligand, name them in
alphabetic order (tetraaquadichloro), end the names of negative ligands in
letter o
5. Name the central (complexing) particle – if the complex ion is a cation ,
use the ordinary name for the metal, if the complex ion is an anion, then end
the name of the metal (latine) in suffix –ate (Co – cobaltate, Cu – cuprate, Fe
– ferate)
6. Denote the oxidation state of the metal by a roman numeral in
parentheses following the name of the metal - ...ferrate (II), ...chromate (0),
...chromate (III)
2017-05-22
prof. V. Paulauskas
11
NAMING OF COMPLEXES
K4[Fe(CN)6]
Potassium hexacyanoferrate (II)
[Al(OH2)6]Cl3
Hexaaquaaluminium (III) chloride
[Fe(CO)5]
2017-05-22
Pentacarbonylferrate (0)
prof. V. Paulauskas
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CLASSIFICATION OF COMPLEXES
According oxidation state of complex ion:
1. Anionic complexes
2. Cationic complexes
3. Neutral complexes
4. Cationic-anionic complexes
[Ni(NH3)6]2[Fe(CN)6]
2017-05-22
prof. V. Paulauskas
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CLASSIFICATION OF COMPLEXES
According the origin of outer sphere:
1. Complex acids – H2[SiF6]
2. Complex bases – [Ag(NH3)2]OH
3. Complex salts – K3[Fe(CN)6]
2017-05-22
prof. V. Paulauskas
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CLASSIFICATION OF COMPLEXES
According to the type of ligands:
1. Aquacomplexes – [Cr(OH2)]Cl3
2. Hydroxocomplexes – Na[Cr(OH)4]
3. Amminocomplexes – [Ag(NH3)2]Cl
2017-05-22
prof. V. Paulauskas
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NAMING – Examples
[Ag(NH3)2]NO3 – diamminesilver (I) nitrate
[Cu(NH3)4]Cl2 – tetraamminecopper (II) dichloride
K3[Fe(CN)6] –
tripotassium hexacyanoferrate (III)
K2[PtCl4] – dipotassium tetrachloroplatinate (II)
Na[Al(H2O)2(OH)4] – sodium diaquatetrahydroxoaluminate (III)
2017-05-22
prof. V. Paulauskas
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NAMING – Examples
Sodium pentahydroxodinitrochromate (III)
- -4
+
+
3
Na4 [Cr (NO2)2 (OH)5 ]
Na4[Cr(NO2)2(OH)5]
2017-05-22
prof. V. Paulauskas
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DISSOCIATION
Cu3[Fe(CN)6]2 ↔ 3Cu2+ + 2[Fe(CN)6]3All complex salts are good electrolytes
2017-05-22
prof. V. Paulauskas
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CHELATING COMPLEXES
Ligands:
• Monodentate (one donor atom – can give only one pair of electrones)
• Multidentate (more than one pair)
• Bidentate (two donor atoms)
• Terminas dentatinis irgi kilęs iš lotyniško žodžio “dens”, reiškiančio dantis
• Vaizdžiai tariant monodentatinis ligandas turi vieną "dantį", bidentatinis –
du "dantis" ir t.t.
• Ligandas prisijungia prie centrinio atomo visais turimais "dantimis"
2017-05-22
prof. V. Paulauskas
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CHELATING COMPLEXES
Ethylendiamine molecule (CH2)2(NH2)2 can give two pairs of
electrones, two donor N atoms – bidentate ligand
[Co(H2N(CH2)2NH2)Cl2]Cl
Diethylendiaminodichlorocobalt (III) chloride
2017-05-22
prof. V. Paulauskas
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CHELATING COMPLEXES
Chelates – compounds having cyclic structure
CH2–NH2

CH2–NH2
-
Cl
3+
Co
Cl
NH2–CH2

NH2–CH2
+
Cl
-
• Chelate - in greek “chela” means crab claws
2017-05-22
prof. V. Paulauskas
21
CHELATING COMPLEXES
Chelating ligand
EthyleneDiammineTetraAcetic acid - EDTA
CH2COONa
H2C - N - CH2COOH
disodium salt – Na2H2EDTA
H2C - N - CH2COOH
CH2COONa
2017-05-22
prof. V. Paulauskas
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CH2COO
-2
Na+
H2C - N - CH2COO
Me
H2C - N - CH2COO
CH2COO
Na+
Na2H2EDTA + Me2+  Na2[MeEDTA] + 2H+
•Me2+ are bonded into chelating metaloorganic complex
•Most of complex compounds of transition metals are colored – used in
chemical analyses
•For bonding and removal of heavy metals from soils, living organisms
2017-05-22
prof. V. Paulauskas
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Application of Complex Compounds
• Formation of metal coating
• Chemical and thermal processing of metals, welding, electrochemical
purification
• Qualitative and Quantitative chemical analysis (Co complexes)
• Removal of heavy metals (Pb, Hg, Cd)
• Manufacturing of farmaceuticals
• Cement industry (hydrates – aquacomplexes)
• Photography
• Biologically important complexes – chlorofile, blood hemoglobine
2017-05-22
prof. V. Paulauskas
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