Cordination Compounds Essay

* FLEXIDENTATE CHARACTER OF POLYDENTATE LIGANDS* Poly dentate ligands have flexi dentate quotation in the sense that all donors atoms may not form organise bonds with the central metal atom or ion. For example EDTA which is the hexa dentate ligand besides acts as tetra dentate or penta dentate in certain interlockinges. also sulphate ion, which is a bi dentate ligand, also acts as a mono dentate ligand in certain complexes, e.g. in Co(SO4)(NH3)5Cl. * LABILE COMPLEXES* A complex in which the ligands can be easily replaced by former(a) ligands is called a labile complex. * GEOMETRY OF CuX42- IONS* The halide complex of Cu (2) shows two different binaural chemistries. In (NH4)2CuCl4, CuCl42- ion is square planar, but Cs2CuCl4 and Cs2CuBr4, the CuX42- ions have a slightly squeeze tetrahedral shape. Tetrahedral CuCl42- ions are orange whereas, square planar CuCl42- ions are yellow in colour. * GREATER STABILITY OF Co(+3) COMPLEXES THAN Co(+2) COMPLEXES * Co+2 ions are very lasting & are difficult to oxidise. Co+3 ions are less(prenominal) stable and are readily reduced by water to carbon dioxide+. In contrast Co(+2) are less stable and are readily oxidised to Co(+3) complexes, i.e. Co(3) are very stable. This is because CFSE of Co(+3) with d6 configuration is higher than Co(+2) with d7 configuration. * SIDGWICK THEORY OR EFFECTIVE ATOMIC NUMBER (EAN) RULE* Sidgwick put forward a manage to explain the stability of complexes on the basis of effective atomic fall as follows- EAN of metal in complex= atomic play oxidation state+2 co-ordination number A stable complex is formed if the EAN is equal to the atomic number of the next noble gas.Thus, from the numeration given in the table below, Fe(CN)64- is more stable than Fe(CN)63- Though this rule is found to be applicable in many cases, yet it fails in no. Of cases as illustrated by last two examples given in the table belowcomplex Oxidation state Atomic number Co-ordination number EAN Co(NH3)63+ +3 27 6 27-3+26=36, i.e. KrFe(CN)64- +2 26 6 26-2+26=36, i.e. KrPtCl62- +4 78 6 78-4+26=86, i.e. RnFe(CN)63- +3 26 6 26-3+26=35Ag(NH3)21+ +1 47 2 47-1+22=50