SUNAYANA

  APPLICATIONS OF CRYSTAL FIELD THEORY Crystal field theory was developed by Hans Bethe(1929) and Van Vleck(1935). This theory ( CFT ) largely replaced Valence Bond Theory for interpreting the chemistry of coordination compounds. Main assumptions in CFT, ·          According to CFT, the interactions between the central metal ion and its ligands are purely electrostatic (ionic). ·          The ligands are treated as point Charges. ·          If the ligand is anionic : ion-ion interaction. If the ligand is neutral : ion-dipole interaction ·          The electrons on metal occupy those d-orbitals farthest away from the direction of approach of ligands. Three p - orbitals Five d - orbitals In octahedral field: dxy, dxz, dyz ▬ t 2g set dz², dx²-y² ▬ e g set Applications of CFT are, 1.    ...

Assignment-Inorganic Chemistry   MACROCYCLES AND AFFINITY OF METAL IONS  TOWARDS MACROCYCLES A macrocycle is defined as a cyclic compound with nine or more members including at least three donor atoms.  Macrocycles are special types of polydentate ligands in which the ligating atoms are constrained in a large ring encircling the metal atom. Macrocycles are important and powerful ligands, ubiquitous in transition metal coordination chemistry for the following reasons:   1) They mimic important biological ligands developed long ago by nature, for example the porphyrin prosthetic group of many metalloproteins.   2) They impart thermodynamic and kinetic stabilities to their metal complexes uncommon or non-existent with ligands of lessor types. Macrocycles can be classified as, a.        Polyaza Macrocycles b.          Polythia, Polyphospha, and Polyarsa Macrocycles c       ...