Structural Application of Refractometry

The refraction of the liquid water is 3.66 cm /mol, indicative of H-bonding. Under shock compression the RI of water increases to 1.60 at P = 22GPa, cf. 1.33 at ambient conditions. This increase, combined as it is with a steep increase of electric conductivity, was once explained by metallization [200]. In fact, it is due simply to higher density of the compressed water theR(H20) = 3.2 cm /mol is actually lower than the ambient and indicates the rupture of H-bonds [201], this results in higher mobility of protons and hence higher conductivity. After the refractometric refutation of the metallic water , this mechanism of conductivity was confirmed directly [202]. 

Refractometric methods are useful for investigating vitfeous or polycrystalline silicates to determine the structural role of anions or to define Nc of cations, since the refraction of the oxide component of the silicate depends on Nc as 

Refractometric method is especially useflil for the study of the rrans-effect in coordination compounds (see Chap. 3). In Pt(II) complexes this increases in the succession 

F NH3 H2O. These radicals can be neatly grouped according to the atom which is bonded to Pt  

The essentially new feature in the above sequence is the difference in tratis-activity shown by those radicals which are capable to isomerize the activity of the SCN, CN, and NO2 groups markedly depends on which end of the ligand is bonded to the central atom. These radicals can be linked differently in the complex compounds of various metals, or even in various compounds of the same metal, and in these cases the order of trani -activity would be considerably different. 

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