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The enthalpy of solvation decreases with increasing ionic radius. Various solid hydrates are known with 8-coordination in square antiprism and dodecahedral geometry. [30] In water, calcium and strontium are most probably eight-coordinate square antiprismatic (although seven-coordination for calcium cannot presently be excluded).
Compared to the first coordination sphere, the second coordination sphere has a less direct influence on the reactivity and chemical properties of the metal complex. Nonetheless the second coordination sphere is relevant to understanding reactions of the metal complex, including the mechanisms of ligand exchange and catalysis.
A classic example is when water molecules arrange around a metal ion. If the metal ion is a cation, the electronegative oxygen atom of the water molecule would be attracted electrostatically to the positive charge on the metal ion. The result is a solvation shell of water molecules that surround the ion.
Electron configuration is also a major factor, illustrated by the fact that the rates of water exchange for [Al(H 2 O) 6] 3+ and [Ir(H 2 O) 6] 3+ differ by a factor of 10 9 also. [4] Water exchange usually follows a dissociative substitution pathway, so the rate constants indicate first order reactions.
This first coordination sphere is encased in further solvation shells, whereby water bonds to the coordinated water via hydrogen bonding. For charged species , the orientation of water molecules around the solute dependent on its radius and charge, [ 1 ] with cations attracting water’s electronegative oxygen and anions attracting the hydrogens.
Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH 3 (aq). Although the name ammonium hydroxide suggests a salt with the composition [NH + 4][OH −
Cisplatin, PtCl 2 (NH 3) 2, is a coordination complex of platinum(II) with two chloride and two ammonia ligands.It is one of the most successful anticancer drugs. A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands ...
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.