Group IA, IIA metal cations

A. Group IA, IIA Metal Cations by Organic Redox-Active Macrocycles... 

We have recently prepared a new chromophoric and redox-responsive ionophore (4) containing a tricyanovinyl redox-active moiety (35) (Scheme 2). Electronic absorption spectra of (4) exhibit hypochromic shifts on binding Group IA and IIA metal cations and cyclic voltamme-tric electrochemical investigations reveal that (4) electrochemically recognizes Na+ and K+ guest cations, resulting in one-wave CV shifts of the tricyanovinyl reduction wave (80 and 20 mV, respectively) to more anodic potentials. 

The elements that form only one cation are the alkali metals (group IA), the alkaline earth metals (group IIA), zinc, cadmium, aluminum, and most often silver. The charge on the ions that these elements form in their compounds is always equal to their periodic table group number (or group number minus 10 in the newest labeling system in the periodic table). 

The sulfides of the group IIA metals generally have the sodium chloride structure, but those of the group IA metals have the antifluorite structure because the ratio of anions to cations is 2. Solutions of the sulfides are basic as a result of the hydrolysis reaction... 

All of the Group IA and IIA metals form sulfides, some of which are used rather extensively. The sulfides of Group IIA metals consist of M2+ and S2 ions arranged in the sodium chloride type lattice (see Chapter 3). The compounds of the Group IA metals consist of M+ and S2, but as a result of there being twice as many cations as anions, the structure is of the antifluorite type (see Chapter 3). The sulfide ion is a base so there is extensive hydrolysis in solutions of the sulfides, and the solutions are basic ... 

Solid perxenate (Xe064-) salts can be obtained that contain cations of Group IA and IIA metals. The Xe064- ion has a very weak conjugate acid (HXeOe3-) so the hydrolysis reactions... 

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