Hydride displacement law

The ammonium ion NH4+ has a tetrahedral structure and is slightly acidic (p/fa = 9.25). If no strong hydrogen bonds are present, like in NH4F, the properties of ammonium salts, for example, the solubility and the structure, are similar to the corresponding potassium and rubidium salts. The reasons are similar ionic radii of the aimnonium (143 pm), potassium (137 pm), and rubidium ions (148 pm). The oxonium salts H30+X , which have lower melting points, are also similar to the ammonium salts. The similar properties of element-hydrogen compounds have been rationalized by the hydride displacement law shown in Table 12. 

The concept of isosters was then broadened by Grimm in 1925 with the statement of Hydride Displacement Law, and, further on, Erlenmeyer extended Grimm s... 

V TABLE 15.2 Hydride Displacement Law In Each Vertical Column the Atom is Followed by its Pseudoatoms ... 

Later, in 1925, Grimm formulated the hydride displacement law , according to which the addition of hydrogen to an atom confers on the aggregate the properties of the atom of the next highest atomic number. An isoelectronic relationship exists among such aggregates which were named pseudoatoms. Thus, when a proton is added to the 0 ion in the nuclear sense, an isotope of fluorine is obtained (Fig. 13.1). 

Table 13.1 Hydride displacement law in each vertical column the atom is followed by its pseudoatoms...

In 1970, Burger classified and snbdivided bioisosteres into two broad categories classic and non-classic. Grimm s Hydride Displacement Law and Erlenmeyer s definition of... 

In 1925, H.G. Grimm [3] extended the concept of isosterism, introduced by Langmuir, with Grimm s hydride displacement law ... 

In 1925, Grimm formulated his hydride displacement law, which states that the addition of a hydride to an atom produces a pseudoatom with the same physical properties as those present in the column immediately behind in the periodic table, as shown in Table 2.2 [2]. 

Table 2.2 Isosteres based on Grimm s hydride displacement law.

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