Techniques of Coordination Compounds

Techniques of Coordination Compounds

Coordination Compounds

History of Coordination Compounds:

            Coordination compounds have been known since the beginning of modern chemistry. Early well-known coordination complexes include dyes such as Prussian Blue. Their properties were first well understood in the late 1800s, following the 1869 work of Christian Wihelm Blomstrand. The Blomstrand theory claimed that the reason coordination complex form is because in solution, ions would be bound via ammonia chain.


Structure of Coordination Compounds:

            The ion or molecule surrounding the central atom are called ligands. Ligands are classified as L or X depending on how many electrons they provide for the bond between ligand and central atom. L ligand provide two electron from a lone electron pair, resulting in a coordinate covalent bond. X ligand provide one electron with a central atom providing the other electron, thus forming a regular covalent bond. The ligands are said to be coordinated to atom.


Properties of Coordination Compounds:

            Many of properties of the transition metal complexes are dictated by their electronic structure. The electronic structure can be described by a relatively ionic model that describes a formal charges to the metal and the ligands. This approach is the essence of CFT Crystal Field Theory. More sophisticated models embrace covalency, and this approach is described by Ligand Field Theory and MOT Molecular Orbital Theory. These theories treats all interactions in complex as ionic and assumes that the ligands can be approximated by negative point charges.

            Coordinate complexes often have spectacular colors caused by electronic transition by the absorption of light.



Coordination compounds have been known since the beginning of modern chemistry.



Applications of Coordination Compounds:

            The coordination compounds have several applications in many fields like;

Ø  

Bioinorganic chemistry:

                        In Bioinorganic Chemistry and Bioorganometallic Chemistry, coordination compounds serve either structure or catalytic functions. As esteemed 30% of protein            contains metal ions.

            e.g: Vitamin B12, the Hemo group In Hemoglobin, the Chlorine group in Chlorophyll as  Cytochrome.

Ø  Industry:

                        Homogenous catalysis is a major application of coordination compounds for the   production of organic substances. Process includes hydrogenation, Hydroformylation,     oxidation.

            e.g: Titanium trichloride and triethylaluminium gives ride to Ziegler-Natta Catalyst used for polymerization of ethylene and propylene to give polymers of commercial importance    as fiber, films and plastics.

Ø  Analysis:

                        At one time coordination compounds were used to identify the presence of metals           in a sample. Qualitative inorganic analysis has largely been suppressed by instrumental         method of analysis such as;

            e.g: Atomic absorption Spectroscopy (AAS), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS)


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