Polyatomic zintl

Polyatomic zintl anions of the post-transition elements. J. D. Corbett, Chem. Rev., 1985, 85, 383 (117). 

Polyatomic Zintl Anions Stabilized Through Crypt Complexation of the Cation... 

Corbett JD (1985) Polyatomic Zintl anions of the post-transition elements. 

NMR studies of solutions of inter-metallic phases led to recognition of the potential use of polyatomic Zintl ions as reagents for the generation of new cluster compounds (Eichhorn et al., 1988). Examples of transition-metal derivatives have been discussed in Chapter 5 and the structures of the ions themselves were used as examples of ligand-free main-group clusters in Chapter 2 (Corbett, 1985 Fassler, 2001). The following examples illustrate recent developments in the chemistry of these clusters derived from solid-state syntheses. 

The term Zintl phase is applied to solids formed between either an alkali- or alkaline-earth metal and a main group p-block element from group 14, 15, or 16 in the periodic table. These phases are characterized by a network of homonuclear or heteronuclear polyatomic clusters (the Zintl ions), which carry a net negative charge, and that are neutralized by cations. Broader definitions of the Zintl phase are sometimes used. Group 13 elements have been included with the Zintl anions and an electropositive rare-earth element or transition element with a filled d shell (e.g. Cu) or empty d shell (e.g. Ti) has replaced the alkali- or alkaline-earth element in some reports. Although the bonding between the Zintl ions and the cations in the Zintl phases is markedly polar, by our earlier definition those compounds formed between the alkali- or alkaline-earth metals with the heavier anions (i.e. Sn, Pb, Bi) can be considered intermetallic phases. 

A.2.2 Nonpolar Binary Intermetallic Phases. Zintl phases are characterized by the presence of markedly heteropolar bonding between the Zintl ions (electronegative polyatomic clusters) and the more electropositive metal atoms. By contrast, the bonding between heteronuclear atoms within other intermetallic compounds is primarily covalent or metallic. A number of different structure types exist for any given... 

Reaction of group 15 elements like arsenic with alkali or alkaline earth metals forms Zintl anions of the general type Asn". Characterization of these species has been accomplished dissolving the solids in liquid NH3 or ethylenediamine (H2NCH2CH2NH2) and adding the macrocycle, 2,2,2-crypt (5) to complex the cations and stabilize the polyatomic anions. The fully characterized Zintl arsenic anions As4, As and Asu are shown inFigme 1. ... 

A number of the intermetallic phases formed between the alkali metals and the heavier posttransition elements (Sn, Pb, As, Sb, Bi, Se, Te) have the very remarkable property of dissolving in liquid ammonia to form very intensely colored solutions. The most extensive characterization of these solutions has been by Zintl and co-workers, who by potentiometric titrations established the apparent formation of polyatomic ions such as Sn -, Bif, and Tel-.1,2 Unfortunately, on evaporation of solvent these salts always revert to the more stable intermetallic phases, for example,... 

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