Werner werner was born on in mülhouse a small

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WernerWernerWernerWernerWernerwas born on December 12, 1866, in Mülhouse,a small community in the French province of Alsace.His study of chemistry began in Karlsruhe (Germany)and continued in Zurich (Switzerland), where in hisdoctoral thesis in 1890, he explained the difference inproperties of certain nitrogen containing organicsubstances on the basis of isomerism. He extended vantHoff’s theory of tetrahedral carbon atom and modifiedit for nitrogen. Werner showed optical and electrical differences betweencomplex compounds based on physical measurements. In fact, Werner wasthe first to discover optical activity in certain coordination compounds.He, at the age of 29 years became a full professor at TechnischeHochschule in Zurich in 1895. Alfred Werner was a chemist and educationist.His accomplishments included the development of the theory of coordinationcompounds. This theory, in which Werner proposed revolutionary ideas abouthow atoms and molecules are linked together, was formulated in a span ofonly three years, from 1890 to 1893. The remainder of his career was spentgathering the experimental support required to validate his new ideas. Wernerbecame the first Swiss chemist to win the Nobel Prize in 1913 for his workon the linkage of atoms and the coordination theory.(1866-1919)(1866-1919)(1866-1919)(1866-1919)(1866-1919)FormulaMoles of AgCl precipitated per mole ofthe compounds with excess AgNO3(i) PdCl2.4NH32(ii) NiCl2.6H2O2(iii) PtCl4.2HCl0(iv) CoCl3.4NH31(v) PtCl2.2NH30Example 9.1Example 9.1Example 9.1Example 9.1Example 9.12015-16(20/01/2015)
240Chemistry(a) Coordination entityA coordination entity constitutes a central metal atom or ion bondedto a fixed number of ions or molecules. For example, [CoCl3(NH3)3]is a coordination entity in which the cobalt ion is surrounded bythree ammonia molecules and three chloride ions. Other examplesare [Ni(CO)4], [PtCl2(NH3)2], [Fe(CN)6]4–, [Co(NH3)6]3+.(b) Central atom/ionIn a coordination entity, the atom/ion to which a fixed numberof ions/groups are bound in a definite geometrical arrangementaround it, is called the central atom or ion. For example, thecentral atom/ion in the coordination entities: [NiCl2(H2O)4],[CoCl(NH3)5]2+ and [Fe(CN)6]3–are Ni2+, Co3+and Fe3+, respectively.These central atoms/ions are also referred to as Lewis acids.(c) LigandsThe ions or molecules bound to the central atom/ion in thecoordination entity are called ligands. These may be simple ionssuch as Cl, small molecules such as H2O or NH3, larger moleculessuch as H2NCH2CH2NH2or N(CH2CH2NH2)3or even macromolecules,such as proteins.When a ligand is bound to a metal ion through a single donoratom, as with Cl, H2O or NH3, the ligand is said to be unidentate.When a ligand can bind through two donor atoms as inH2NCH2CH2NH2(ethane-1,2-diamine) or C2O42–(oxalate), theligand is said to be didentateand when several donor atoms arepresent in a single ligand as in N(CH2CH2NH2)3, the ligand is saidto be polydentate. Ethylenediaminetetraacetate ion (EDTA4–) isan important hexadentate ligand. It can bind through two

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