Saba (023) BOOK REVIW

NAME:SABA SALAMAT
ROLL NO:19104008-023
MAAM MADIHA
BOOK REVIEW
06-JAN-2022
Topic:
Coordination compounds
Coordination compound, any of a class of substances with chemical structures in
which a central metal atom is surrounded by nonmetal atoms or groups of atoms,
called ligands, joined to it by chemical bonds. Coordination compounds include
such substances as vitamin B12, hemoglobin, and chlorophyll, dyes and pigments,
and catalysts used in preparing organic substances.
A major application of coordination compounds is their use as catalysts, which

serve to alter the rate of chemical reactions. Certain complex metal catalysts, for
example, play a key role in the production of polyethylene and polypropylene. In
addition, a very stable class of organometallic coordination compounds has
provided impetus to the development of organometallic chemistry.
Organometallic coordination compounds are sometimes characterized by
“sandwich” structures, in which two molecules of an unsaturated cyclic
hydrocarbon, which lacks one or more hydrogen atoms, bond on either side of a
metal atom. This results in a highly stable aromatic system.
The following article covers the history, applications, and characteristics (including
structure and bonding, principle types of complexes, and reactions and syntheses)
of coordination compounds. For more information about specific properties or
types of coordination compounds, see the articles isomerism; coordination
number; chemical reaction; and organometallic compound.
Electric Configuration:
The CFSE of a complex can be calculated by multiplying the
number of electrons in t2g orbitals by the energy of those orbitals (−0.4Δo),
multiplying the number of electrons in eg orbitals by the energy of those orbitals
(+0.6Δo), and summing the two. The reaction of one or more ligands with a metal
ion to form a coordination compound. redox: A reversible chemical reaction in
which one reaction is an oxidation and the reverse is a reduction. donor atom:
The atom within a ligand that is bonded to the central atom or ion within a
coordination complex. The spin-pairing energy (P) is the increase in energy that
occurs when an electron is added to an already occupied orbital. A high-spin
configuration occurs when the Δo is less than P, which produces complexes with
the maximum number of unpaired electrons possible.
Nomenclature of Coordinate Compounds:
A complex is a substance in which a metal
atom or ion is associated with a group of neutral molecules or anions called
ligands. Coordination compounds are neutral substances (i.e. uncharged) in which
at least one ion is present as a complex. You will learn more about coordination
compounds in the lab lectures of experiment 4 in this course.
The coordination compounds are named in the following way. (At the end of this
tutorial we have some examples to show you how coordination compounds are
named.) To name a coordination compound, no matter whether the complex ion
is the cation or the anion, always name the cation before the anion. (This is just
like naming an ionic compound.)
1. Name the ligands first, in alphabetical order, then the metal atom or ion. Note:
The metal atom or ion is written before the ligands in the chemical formula.
2. The names of some common ligands are listed in Table 1.
For anionic ligands end in "-o"; for anions that end in "-ide"(e.g. chloride), "-
ate" (e.g. sulfate, nitrate), and "-ite" (e.g. nirite), change the endings as follows: -
ide -o; -ate -ato; -ite -ito.
For neutral ligands, the common name of the molecule is used e.g.
H2NCH2CH2NH2 (ethylenediamine). Important exceptions: water is called ‘aqua’,
ammonia is called ‘ammine’, carbon monoxide is called ‘carbonyl’, and the N2 and
O2 are called ‘dinitrogen’ and ‘dioxygen’.
EAN Rule:
Effective atomic number (EAN), number that represents the total
number of electrons surrounding the nucleus of a metal atom in a metal complex.
... The EAN rule is often referred to as the “18-electron rule” since, if one counts
only valence electrons (6 for Co3+ and 2 × 6 = 12 for 6 NH3), the total number is
18.
Effective Atomic Number in Coordination Compounds:

In the above definition, we explain effective atomic number concept. This concept
explains the stability and the possibility of complex compound formation.
According to this concept, only that complex compound can be formed that will
attain the noble gas configuration.
D-block element atomic number
Scandium (Sc)- 21
Titanium (Ti)- 22
Vanadium (V)- 23
Chromium (Cr)-24
Manganese (Mn)- 25
Iron (Fe)- 26
Cobalt (Co)- 27
Nickel (Ni)- 28
Copper (Cu)- 29
Zinc (Zn)- 30
Krypton (Kr)- 36
The Nobel gas close to this series is 36. All these elements are less stable than the
krypton. Therefore, all these above-mentioned elements will try to attain this
electronic configuration. For this noble gas configuration, these elements will
form a complex compound with different types of the ligand.
Example:
The oxidation state of iron is zero.
The atomic number of iron is 26.
Carbonyl (CO) is a monodentate ligand.
EAN for the iron will be = an Atomic number of iron + total number of electrons
donated by the ligand.
EAN of iron (Fe) = 26 + 5 *2
EAN of iron (Fe) = 26 + 10
EAN of iron (Fe) = 36.
36 is the noble gas electronic configuration

Werner’s Theory:
Werner's theory states that:
1. Metals possess two types of valencies called primary / ionizable and

secondary / non - ionizable valency.
2. Every metal atom has a tendency to satisfy both its primary and secondary.
Postulates:
 The central metal or the metal atoms in coordination compounds
show two types of valency. They are the primary and secondary
valency.
 The primary valency relates to the oxidation state and the
secondary valency relates to the coordinate number.
 The number of secondary valences is fixed for every metal atom. It
means that the coordination number is fixed.
 The metal atom works towards satisfying both its primary and
secondary valencies. A negative ion satisfies the primary valency.
On the other hand, a negative ion or neutral molecules satisfy
secondary valencies.
Valence bond theory:

According to the valence bond theory,Electrons in a
molecule occupy atomic orbitals rather than the molecular orbitals. The
atomic orbitals overlap on the bond formation and the larger the overlap
the stronger the bond.
The metal bonding is essentially covalent in origin and metallic structure

involves resonance of electron-pair bonds between each atom and its
neighbors.
Jahn-Teller theorem:
The Jahn–Teller theorem essentially states that any non-linear
molecule with a spatially degenerate electronic ground state will undergo a
geometrical distortion that removes that degeneracy, because the distortion
lowers the overall energy of the molecule.
Example:
The result is a pseudo Jahn–Teller effect, for example, of an E state
interacting with an A state. This situation is common in JT systems, just as
interactions between two nondegenerate electronic states are common for non-
JT systems. Examples are excited electronic states of NH3+ and the benzene
radical cation.
Crystal Field Theory:

Crystal field theory (CFT) describes the breaking of
degeneracies of electron orbital states, usually d or f orbitals, due to a static
electric field produced by a surrounding charge distribution (anion neighbors).
CFT was developed by physicists Hans Bethe and John Hasbrouck van Vleck in the
1930s.
Crystal field theory (CFT) is a bonding model that explains many important
properties of transition-metal complexes, including their colors, magnetism,
structures, stability, and reactivity. The central assumption of CFT is that metal–
ligand interactions are purely electrostatic in nature.

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NAME:SABA SALAMAT

A major application of coordination compounds is their use as catalysts, which

2. The names of some common ligands are listed in Table 1.

Effective Atomic Number in Coordination Compounds:

D-block element atomic number

The atomic number of iron is 26.

Carbonyl (CO) is a monodentate ligand.

EAN of iron (Fe) = 26 + 5 *2

EAN of iron (Fe) = 26 + 10

EAN of iron (Fe) = 36.

36 is the noble gas electronic configuration

1. Metals possess two types of valencies called primary / ionizable and

Valence bond theory:

The metal bonding is essentially covalent in origin and metallic structure

Crystal Field Theory:

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