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SUBJECT-CHEMISTRY


                                        CHAPTER-COORDINATION COMPOUNDS


                          SUBTOPIC- CFT,MAGNETIC PROPERTY,COLOUR,STABILITY AND METAL
                          CARBONYLS

                    KEY NOTES:

                        The crystal Field Theory (CFT) to co-ordination compounds is based on
                          the  effect  of  different  crystal  fields,  on  the  degeneracy  of  d-orbital
                          energies of the central metal atom/ion. The splitting of the d-orbitals
                          providers different electronic arrangements in strong and weak fields.
                        The treatment (CFT) provides for quantitative estimations of orbitals
                          separation  energies,  magnetic  moments  and  spectral  and  stability
                          parameters.  However  the  assumption  that  ligands  constitute  point
                          charges creates many theoretical difficulties.

                        The  metal-carbon  bond  in  metal  carbonyls  possesses  both  and        s
                          character. The ligand to metal is 6 bond and metal to ligand is       bond.
                          This unique synergic bonding provides stability to metal carbonyls.

                        Co-ordination  compounds  are  of  great  importance.  These
                          compounds provide critical insights into the functioning and
                          structures of vital components of biological systems.

                        These  compounds  also  find  extensive  applications  in
                          metallurgical processes, analytical and medicinal chemistry.
                        Colour of the coordination compounds is due to presence of unpaired
                          electrons which undergo d-d transition.
                         The homoleptic carbonyls (compounds containing carbonyl ligands only)
                          are formed by most of the transition metals. These carbonyls have
                          simple, well defined structures.Tetracarbonylnickel(0) is tetrahedral,
                          pentacarbonyliron(0) is trigonalbipyramidal while hexacarbonyl
                          chromium(0) is octahedral.
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