# 9.3     Explain with two examples each of the following: coordination entity, ligand, coordination number, coordination polyhedron, homoleptic and heteroleptic.

(i) Coordination entity:-   It is an electrically charged species carrying either a positive charge or a negative charge. In a coordination entity, the central atom or ion is surrounded by some number of neutral molecules or negative ions ( called ligands) accordingly.

$E.g\ \left [ PtCl_4 \right ]^{2-}\ and\ \left [ Ag(CN)_2 \right ]^{-}$

(ii) Ligand:- Ligands are the neutral molecules or negatively charged ions that surround the metal atom in a coordination entity according to the holding capacity of central metal ion are known as ligands. NH3  and  H2O are two neutral ligands.

(iii) Coordination number:-  The total number of metals that surrounds the central metal ion is known as coordination number.

For e.g,(a) In case of $\left [ PtCl_6 \right ]^{2-}$six chlorine atoms are attached to Pt, thus the coordination number of the given compound is 6.

(b) In case of $\left [ Ni(NH_3)_4 \right ]^{2-}$ the central metal ion Ni is surrounded by 4 atoms of ligand so its coordination number is 4.

(iv)  Coordination polyhedron:-  It is defined as the spatial arrangement of the ligands which are directly attached to the central metal ion/atom.

E.g.  square planar,  tetrahedral.

(v) Homoleptic:-  Homoleptic compounds are defined as the compounds in which the donor/ligand attached to central metal atom/ion is of one kind.

E.g.   $\left [ PtCl_6 \right ]^{2-}$  and   $\left [ Ni(NH_3)_4 \right ]^{2-}$

(vi) Heteroleptic:-  These are the coordination compounds in which central atoms are attached with more than one type of ligand.

E.g.   $\left [ Co(NH_3)_5Cl \right ]^{2+}$      and   $\left [ Co(NH_3)_4 Cl_2\right ]^{+1}$

## Related Chapters

### Preparation Products

##### JEE Main Rank Booster 2021

This course will help student to be better prepared and study in the right direction for JEE Main..

₹ 13999/- ₹ 9999/-
##### Rank Booster NEET 2021

This course will help student to be better prepared and study in the right direction for NEET..

₹ 13999/- ₹ 9999/-
##### Knockout JEE Main April 2021 (Easy Installments)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 4999/-
##### Knockout NEET May 2021

An exhaustive E-learning program for the complete preparation of NEET..

₹ 22999/- ₹ 14999/-