Importance and Applications of Coordination Compounds 1. They are used in many qualitative and quantitative analysis. 2. Hardness of water is estimated by simple titration with Na2 EDTA.
3. Purification of metals can be achieved through formation and subsequent decomposition of their coordination compounds. 4. They have great importance in biological systems. 5. They are used as catalyst for many industrial processes.
6. In medicinal chemistry, there is a growing interest of chelating therapy.
Organometallic Compounds
They contain one or more metal-carbon bond in their molecules. They are of the following types:
1. Sigma( σ) bonded compounds
Metal-carbon bond is sigma bond, e. g.,( C2H5) 4 Pb, Zn( C2H5) 2 R – Mg – X, etc.
2. Pi( π) bonded compounds
In which molecules / ions containing π bonds act as a ligand. e. g., Ferrocene, Dibenzene chromium and Zeise’ s salt.
Zeise’ s salts is K [ PtCI3( η 2 – C2H4)] In which ethylene acts as a ligand which do not have a lone pair oi electron.
In ferrocene, Fe( η 5 – C5H5) 2 represents the number of carbon atoms with which metal ion is directly attached.
3. σ and π bonded compounds
Metal carbonyls are their examples. Metal-carbon bond of metal carbonyls have both σ and π – bond character. They have CO molecule as ligand, e. g.,
Wilkinson’ s catalyst( Rh( PPh3) 3CI ] is used as homogeneous catalyst in the hydrogenation of alkenes. Zeigler-Natta catalyst
[ Ti CI4 +( C2H5 > 3Al ] acts as heterogeneous catalyst in the polymerisation of ethylene