Isomers hydration

FIGURE 16.19 Hydrate isomers. In part (a), the water molecule is simply part of the surrounding solvent in part (b), the water molecule is present in the coordination sphere and a ligand (green sphere) is now present in the solution. 

Self-Test 16.4A When excess silver nitrate is added to 0.0010 mol CrCl3-6H20 in aqueous solution, 0.0010 mol AgCl is formed. Which hydrate isomer is present ... 

Hiroshima, 721 histidine, 443, 774 hole, 195 homeostasis, 386 HOMO, 126, 580 homogeneous alloy, 202 homogeneous catalyst, 565 homogeneous equilibria, 362 homogeneous mixture, F53 homolytic dissociation, 80 homonuclear diatomic molecule, 103 Hooke s law, 92 hormone, 670 horsepower, A4, 791 hour, A4 HPLC, 354 HRF products, 723 HTSC, 192 Humphreys series, 51 Hund, F 35 Hund s rule, 35, 37 Hurricane Rita, 144 hyaluronic acid, 344 hybrid orbital, 109 hybridization bond angle, 131 molecular shape, 111 hydrangea color, 463 hydrate, F32 hydrate isomer, 676 hydration, 178 hydrazine, 627... 

Hydrate isomers are a special type of ionization isomer. They differ by an exchange between an HzO molecule and another ligand in the coordination sphere (Fig. 16.24). For example, the solid hexahydrate of chromium(III) chloride, CrCl3-6H20, may be any of the three compounds... 

Write the formulas for the hydrate isomers of a compound having the empirical formula CoC13-6H20 and a coordination number of 6. 

Example CuS04-5H20. hydrated Having water molecules attached, hydrate isomers Isomers that differ by an exchange of an H20 molecule and a ligand in the coordination sphere, hydration (1) (of ions) The attachment of water molecules to a central ion. (2) (of organic compounds) The addition of water across a multiple bond (H to one carbon atom, OH to the other). Example ... 

In some crystalline complexes, water can be inside and outside the coordination sphere. For example, when treated with excess AgN03(aq), solutions of the following three hydrate isomers yield three, two, and one mole of AgCl precipitate, respectively, per mole of complex. 

Hydrate isomers Isomers of crystalline complexes that differ in terms of the presence of water inside or outside the coordination sphere. 

Structural (constitutional) isomers (Applied to coordination compounds.) Isomers whose differences involve more than a single coordination sphere or else different donor atoms they include ionization isomers, hydrate isomers, coordination isomers, and linkage isomers. 

Write the formula for a potential hydrate isomer of each of the following compounds. Name each one. 

Hydrate isomers the complexes possible for the empirical formula CrCl3-6H20. In addition, the neutral and 1 + compounds on the left may in principle exist as two geometric isomers, of which only one is shown. 

Hydration isomers result from the interchange of H2O and another ligand between the first coordination sphere and the ligands outside it. 

Hydration isomers. Hydration isomers exist for crystals of complexes containing water molecules, for example CrCl3z6H20. This compound can exist in three different crystalline forms, in which the number of water molecules directly attached to the Cr ion differs. 

Both these papers describe the nse of qnantum chemical and molecnlar dynamics simulations to stndy the stractnre of the first and second coordination spheres of Th(IV) and to determine the residence time of water in the second coordination sphere. In the second paper the authors discuss the entry of chloride into the second coordination sphere at different concentrations of chloride. The starting point in these studies is the determination of the geometry and relative energy of different hydration isomers of Th(IV) nsing ab initio quantnm mechanics. When the ratio (H20)/(Th" ) is nine, the most stable stractnre, [ Th(H20)g" ] has a geometry (a capped square antiprism). 

CrCls 6 H2O is a classic example. Three different crystalline compounds that each feature 6-coordinate Cr(III) have this empirical formula [Cr(H20)6]Cl3 (violet), [CrCl(H20)5]Cl2 H2O (blue-green), and [CrCl2(H20)4]Cl 2 H2O (dark green). These three hydrate isomers can be separated from commercial CrCls 6 H2O, with trans-[CrCl2(H20)4]Cl 2 H2O the major component. Other examples of hydrate isomers are ... 

FIGURE 9.20 The cations [c/s-Ni(phen)2CI(H20)]+ and [c/s-Ni(phen)2(H20)2]2+ co-crystallize with three PFg" counterions and HjO solvate molecules (not shown). If the counterions were Cl , these would be hydrate isomers. (Molecular structure drawing created from CIF data, with hydrogen atoms omitted for clarity.)... 

Compounds with the same formula, but which give different ions upon dissociation, exhibit ionization isomerization. The difference is in which ion is included as a ligand and which is present to balance the overall charge. Some examples are also hydrate isomers ... 

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