Pseudobinary ionic compounds

Some compounds contain polyatomic ions that behave much like monatomic anions. Compounds that contain these ions are called pseudobinary ionic compounds. The prefix pseudo- means false these compounds are named as though they were binary compounds. The common examples of such polyatomic anions are the hydroxide ion, OH , and the cyanide ion, CN. The ammonium ion, NH4+, is the common cation that behaves like a simple metal cation. 

Pseudobinary ionic compound A compound that contains more than two elements but is named like a binary compound. 

The hydrides formed in reaction (a) may be classified as (1) saline or ionic hydrides, (2) metallic hydrides and (3) covalent hydrides. The saline hydrides include the hydrides of the alkali and alkaline-earth metals, except BeHj, which is covalent. Transition metals form binary compounds with hydrogen that are classified as metallic hydrides including rare-earth and actinide hydrides. Intermetallic compound hydrides, such as TiFeHj and LaNijH, may be thought of as pseudobinary metallic hydrides. 

I. Electronic and lattice properties. In this section the electronic properties of magnetically ordering divalent EuSe arc altered by introducing TmSe, provoking possible intermediate valence. In this pseudobinaiy alloy system the substitution of Eu by Tm decreases the lattice constant, but since divalent Tm has a smaller ionic radius than divalent Eu there is no lattice pressure exerted on Tm as long as the compounds are semiconductors (see fig. 106). Thus Tm as well as Eu remain divalent. Kaldis et al. (1982) have shown that in the pseudobinary alloy system a number of miscibility gaps exist, but at x = 0.2 a compositionally induced SMT is found, i.e., for x <0.2 the compounds... 

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