Co-Ordination Compounds
Name :- RISHI RAM MAHATOExam Roll No :- 14SCHE024547Class Roll No :- 146Session :- 2014-17
IntroductionCoordination refers to the "coordinate covalent bonds" (dipolar
bonds) between the ligands and the central atom. Hence, in this type of compounds a electron rich species donates its electron pair/pairs to the electron deficient species.
Coordination complexes have been known since the beginning of modern chemistry. Early well known coordination complexes include dyes such as Prussian blue.
In 1869, WILHELM BLOMSTRAND proposed the COMPLEX ION CHAIN THEORY.
Again it was improved by SOPHUS JORGENSEN.
*Alfred Warner was first to publish the most accepted theory of Complexes in 1893.
History
OccurrenceChlorophyll :- It’s a complex of Mg(II) directly
coordinated with Nitrogen with large Organic entity.Found in Leaves & Green parts of Plants.Plays vital role in existence of Living Things.
Hemoglobin :- It is Complex of Fe(II) directly linked to Nitrogen atoms of large organic entity (HEME structure).
This species is responsible for Red Coloration of Blood.It maintain the pH of the Blood as well.
Cytochrome :- Cytochromes are iron containing hemeproteins central to which are heme groups that are primarily responsible for the generation of ATP via electron transport.
They are found either as monomeric proteins (e.g., cytochrome c) or as subunits of larger enzymatic complexes that catalyze redox reactions.
Fluorite (also called fluorspar) :- is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. Fluorite is a colorful mineral, both in visible and ultraviolet light, and the stone has ornamental and lapidary uses.
Types According to their Geometry, These are classified as Linear for 2 coordination
Trigonal planar for 3 coordination
Tetrahedral or square planar for 4 coordination
Trigonal bipyramidal or square pyramidal for 5 coordination
Octahedral (orthogonal) for 6 coordination
Pentagonal Bipyramidal, capped octahedral or capped trigonal prismatic for 7 coordination
Square antiprismatic or dodecahedral for 8 coordination
Electrostatic model for bonding in transition metal complexes.Accounts for observed properties of transition metal
complexes.Focuses on d-orbitals.Ligands = point charges in case of anions or dipoles in case
of neutral molecules.Assumes metal ligand bond to be ionic.
Crystal Field Theory
Electrostatic Interactions(+) metal ion attracted to (-) ligands (anion or dipole provides stability
lone pair e-’s on ligands repulsed by e-’s in metal d orbitals interaction called crystal field influences d orbital energies
(not all d orbitals influenced the same way)
dx2-y2 dz2
dxy dxz dyz
X
Y Z
X
Y
X
Z
Y
Z
X
Greater Electrostatic Repulsion = Higher Potential Energy
Lobes Directed At Ligands
In Tetrahedral Complexes
dx2-y2 dz2
dxy dxz dyz
X
Y Z
X
Y
X
Z
Y
Z
X
less electrostatic repulsion = lower potential energy
Lobes directed between ligands
In Octahedral Complexes
Ligands Approach Along x, y, z Axes
(-) Ligands Attracted To (+) Metal Ion; Provides Stability
Octahedral Crystal Field
D Orbital E-’s Repulsed By (–) Ligands; Increases D Orbital
Potential Energy
+
-- -
--
-
PropertiesColors Of Transition Metal Complexes
1)A complex must have partially filled d subshell on metal to exhibit color.
2)A complex with 0 or 10 d e-s is colorless.3)Compounds/complexes that have color absorb specific wavelengths of visible light (400 –700 nm).4)Absorption of UV-visible radiation by atom, ion, or molecule:-
Occurs only if radiation has the energy needed to raise an e-
from its ground state to an excited state. i.e., from lower to higher energy orbital
5)wavelengths not absorbed are transmitted6)color observed = complementary color of color absorbed
Absorbed Color
Observed Color
Cis-Platin :-(Cisplatin, Cisplatinum, Platamin, Neoplatin, Cismaplat or Cisdiamminedichloridoplatinum(ii) (CDDP) is a Chemotherapy Drug. It was the first member of a class of platinum containing anticancer drugs, which now also includes carboplatin and oxaliplatin. These platinum complexes react in the body, binding to DNA and causing the DNA strands to crosslink, which ultimately triggers cells to die in a programmed way.The compound is on the World Health Organization's List of Essential Medicines, a list of the most important medications needed in a basic health system.