Coordination chemistry came about from the work of Alfred Werner, a Swiss chemist who examined different compounds made up of cobalt (III) Chloride and ammonia. When hydrochloric acid was added, Werner noticed that ammonia could not be removed completely. He then suggested that the ammonia must bind more tightly to the central cobalt ion. However, when aqueous silver nitrate was added, one of the products formed was solid silver chloride. The resulting amount of silver chloride was related to the number of ammonia molecules bounded to the cobalt (III) chloride. For example, when silver nitrate was added to CoCl3•6NH3, all three chlorides were converted to silver chloride. When silver nitrate was added to CoCl3•5NH3, only 2 of the 3 chlorides formed silver chloride. When CoCl3•4NH3 was treated with silver nitrate, only one of the three chlorides precipitated as silver chloride. The resulting observations gave out the formation of complex or coordination compounds. In the inner coordination sphere, which is also referred to as the first sphere, ligands are directly bound to the central metal. In the outer coordination sphere, sometimes called the second sphere, other ions are attached to the complex ion. The following table is a summary of Werner's observations:
INITIAL COMPOUND RESULTING COMPOUNDS UPON ADDING AgNO3
CoCl3•6NH3
[Co(NH3)6]3+(Cl-)3
CoCl3•5NH3 [Co(NH3)5Cl]2+(Cl-)2
CoCl3•4NH3 [Co(NH3)4Cl2]+(Cl-)
CoCl3•3NH3 [Co(NH3)3Cl3]
A coordination compound or complex is a formed when a ligand is attached to an acceptor by means of a lone pair of electrons (Rajbir Singh, 2002). Coordination compounds are formed between a metal ion and a molecule with one or more unshared electron pairs, called a ligand. According to (Geoaffrey A. L...
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...o living organisms. Metal complexes play a variety of important roles in biological systems. Many enzymes and the naturally occurring catalysts that regulate biological processes are metal complexes (metalloenzymes); for example, carboxypeptidase, is a hydrolytic enzyme that is important in digestion. It contains a zinc ion coordinated to several amino acid residues of the protein. Another enzyme known as catalase, which is an important catalyst for the decomposition of hydrogen peroxide, contains iron-porphyrin complexes. In both these cases, the coordinated metal ions are most probably the sites of catalytic activity. From the research above, a conclusion can be that coordination compounds affect almost all aspects of life, from organisms to daily life. This therefore means coordination compounds are very important and without them, life basically does not exists.
2. Cooper, M. M., Cooperative Chemistry Laboratory Manual, McGraw-Hill: New York, NY, 2009, p. 60.
In our experiment we utilized the hydrate cobaltous chloride. Hydrates are crystalline compounds in which one or more molecules of water are combined with each unit of a salt. Cobalt (II) chloride hexahydrate is an inorganic compound which is a deep rose color in its hydrated form. As an inducer of
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In this case, the nitrate ion moved from one compound to another as the Cu was replaced by Zn. The zinc dissolved to form zinc (II) ions as the copper (II) ions came out of the solution as copper metal and deposited on the surface of the
One of these concepts had to do with solutions – a mixture composed of minor ingredients and a major ingredient, respectively, the solute and the solvent. In the experiment, CuxOy was mixed with HCl to create a copper oxide solution; the result of the mixture was copper chloride and water. By putting both compounds together, a double displacement reaction occurred. This sort of reaction happens when two ionic compounds switch anions and cations to form new ionic compounds. However, not only is this a displacement reaction, but it is also a neutralization reaction – a reaction with an acid and a base that forms salt and water. By reacting CuxOy with HCl, respectively a base and an acid, CuCl (a salt) and H2O was formed. In addition, a single displacement reaction occurred right after Zn was introduced to the solution. Rather than two ionic compounds reacting, the single displacement reaction happens when an element reacts with an ionic compound. The element forms a new compound with one of the components of the other compound, leaving a new compound and a new lone element; in the case of this experiment, CuCl reacted with Zn to create zinc chloride and elemental copper. This was done as a way to isolate the copper so that it can be weighed later. Nonetheless, once at the weighing stage, Cu was laced with water and isopropyl alcohol. To fully isolate the Cu, both the water and
Since the discovery of cisplatin, thousands of platinum complexes were evaluated, but only five were approved. Consequently, more than 10000 compound need to be screened so as to get a novel and more effective anticancer drug than cisplatin with the aid of inorganic or coordination chemistry. Solubility, reactivity, electronic and steric effects, and the configuration of metal complexes can be controlled by modifying the metal to other transition metal such as Pd and Ni or the ligand around the metal atom which has been reported that both the metal and the ligand can determine the biological activity. Hopefully we can find more efficient drugs that may contain much less side effects than cisplatin, as well as solve the problem of overcoming drug resistance of some cancers to cisplatin.
of a zwitterion is made possible due to the basic properties of the NH2 group
Varying the n value carries out the experiment. Absorbencies of each of the ZLn complexes are obtained. The sum of the concentrations of the metal, Z, and the ligand, L, are kept equal. With the ratio of the ligand to the metal in the solution with the maximum absorbance for the ZLn complex, the value of n can be determined as well as the composition of ZLn.
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
V. Amarnath, D. C. Anthony, K. Amarnath, W. M. Valentine, L. A. Wetterau, D. G. J. Org. Chem. 1991, 56, p. 6924-6931.
(Khan): further states, here L are the Ligand and which is formed via the complete replacement of water molecules by other ligands can occur till the formation of the MLn complex. “n” is the coordination number of the metal ion and represents the maximum number of monodentate ligands which can be bound to it [8]
It has been suggested in many different studies that these active complexes of Zn²⁺ ions with accelerators are more reactive than the free accelerator.
In chemistry, metals compose a great number of the periodic table elements. Each metal has its own characteristic mass,
Zinc is an essential trace element for many living organisms. While this can be said about other essential metals, zinc is unique in its physiochemical properties that give it the ability to interact with donor groups of different ligands, resulting in a broad range of stability constants and diversity of the biological functions and processes that zinc is involved in. It was discovered and recognized as a new metal in the eightieth century, While its biological essentiality was found by Raulin for the growth of Aspergillus niger In 1869 [1]. In 1933 Zinc was found essential for the growth of animals while studying its effect on rats. [2]
Boston: Unwin Hyman, 1988. Works Consulted -. Sazlberg, Hugh W. From Caveman to Chemist: Circumstances and Achievements. Washington, D.C.: American Chemical Society, 1991.