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