Coordination Chemistry: Isomerism in Coordination Compounds, Study notes of Chemistry

Download Coordination Chemistry: Isomerism in Coordination Compounds and more Study notes Chemistry in PDF only on Docsity!

Coordination Chemistry: PartCoordination Chemistry: Part

Prepared by

Dr. Chanchal Haldar Dr. Chanchal Haldar

& Dr. R P John & Dr. R P John

Indian Institute of Technology (ISM) Dhanbad

• Recommended Books
• (^) Shriver Atkins Inorganic Chemistry byAtkins, Overton, Rourkee, Weller and Armstrong, Oxford Univ. Press, 4th Ed,

• Inorganic Chemistry: Principle, structure and reactivity , by J. E. Huheey, E. A. Keiter and R. L. Keiter, Harper Collins, 4th Ed,

• Principles of Inorganic Chemistry by Pri, Sharma and Kalia, Milestone publishers
• Basic Inorganic Chemistry, J. D. Lee, Wiley Blackwell, 2008

Color of transition metal complexes Ruby : Al 2 O 3 With Impurity of Chromium Sapphire: Al 2 O 3 with and Impurity titanium and iron impurities are present together, and in the correct valence states, the result is a deep-blue color. Fe2+^ and Ti4+^ ions are substituted for Al3+ Emerald is a gemstone and a variety of the mineral beryl (Be 3 Al 2 (SiO 3 ) 6 ) colored green by trace

Naturally Occurring Coordination Compounds

Given a problem, how will you identify type and no. of isomers a molecule may possess? 7

ISOMERISM IN COORDINATION COMPOUNDS Two or more different compounds having the same formula are called isomers. Two principal types of isomerism are known among coordination compounds. Each of which can be further subdivided.

1. Structural Isomerism a)Coordination isomerism b)Ionization isomerism c)Hydrate isomerism d)Linkage isomerism
2. Stereoisomerism: a)Geometrical isomerism b)Optical isomerism 8

c) Hydrate isomerism: Hydrate (solvent) isomerism occurs when water (or another solvent) can appear within the primary or secondary coordination sphere of a metal ion The best known example of this occurs for chromium chloride "CrCl 3 .6H 2 O" which may contain 4, 5, or 6 coordinated water molecules. d) Linkage isomerism: Occurs with ambidentate ligands. These ligands are capable of coordinating in more than one way. The best known cases involve the monodentate ligands SCN- / NCS- and NO 2

• / ONO - . [Co(ONO)(NH 3 ) 5 ]Cl nitrito isomer -O attached [Co(NO )(NH ) ]Cl nitro isomer - N attached. 10

11

Linkage Isomers Linkage Isomers

13

Octahedral: Compound type No. of isomers Ma 4 b 2 2 (cis- and trans-) Ma 3 b 3 2 (fac- and mer-) MAA 2 b 2 3 (2cis- and 1 trans-) here a, and b, represent monodentate ligands and AA is a bidentate ligand.* 14

M a a b b a a Cis- M b a b a a a trans-

3. Ma 4 b 2 M a a b b b a M b a b a b a mer- f ac-
4. Ma 3 b 3

M

a

a b

b

a

c

f ac-

M

a

c b

b

a

a

M

a

b c

b

a

a

cis- trans-

mer-

4. Ma 3 b 2 c mer- M a a b c a d f ac- M a c b d a a M a b c d a a M a b d c a a
5. Ma 3 bcd

19

Optically active square planar complex:Optically active square planar complex: Pt N H H N H N N H C C C 6 H 5 H H C 6 H 5 C C CH 3 CH 3 H H 2 +