Zintl ions anions

In a review, Van der Lugt (1996) observed that a number of liquid alloys (K-Pb, Rb-Pb, Cs-Pb, K-Sn, Rb-Sn, Cs-Sn, K-Te) behave as if all the anions were in the form of perfect simple Zintl anions like tetrahedra and dumbbells this being suggested by the behaviour of many physical properties (resistivity, thermodynamic properties, etc.) as a composition function. In this context a simple Zintl ion was defined as a polyanion that assumes the same configuration as a neutral isoelec-tronic element. A similar definition was reported by Van der Lugt and Verkerk... 

Zintl ions are polyanions formed by anion clustering in ionic alloys. Two categories were considered those that fit the so-called Zintl-Klemm concept and those that are electron-deficient. 

The efforts to rationalize the formulas and structures of Zintl ions and related species predated extensive definitive structural information on anionic post-transition metal clusters obtained by Corbett and his group in the 1970s [8, 9]. After enough such structural information on the bare post-transition metal clusters became available, the resemblance of their polyhedra to the known polyhedral boranes became apparent. For this reason, the simple Zintl-Klemm concept has been largely superseded by newer, more advanced descriptions of chemical bonding in such clusters, initially those applied to the polyhedral boranes. 

Zintl ions isostractural Ir-I derivatives of the nido-Eg anions (E = Sn, Pb). Eur J Inorg... 

Relationships Between Soluble Zintl Anions, Ligand-Stabilized Cage Compounds Table 10 Relation of Zintl ions and ligand-stabilized cage compounds 125... 

A nucleophilic metal anion has been used as a reducing agent to create Zintl ion directly. [PPN]2[Fe2(CO)6(Te2)2] (169) has been synthesized by direct reaction of Na2[Fe(CO)4] with elemental tellurium.115 Although not structurally characterized by X-ray methods, the formulation of 169 is supported by several pieces of experimental evidence. It can react with itself or with the Zintl ions present to produce mixed-metal species. It reacts with iodomethane to yield [Fe2(CO)6(/z-TeMe)2] (170) (Fig. 56),... 

Indium and thallium form a number of binary compounds with alkali metals in which the group 13 elements form well-defined anionic clusters (Zintl ions, see Section 1-9). Examples are K8Inu (Fig. 6-3) which has considerably fewer (2n-4) electrons than the minimum described by Wade s rules (2n + 2), KgIn10Zn and K10In10M (M = Ni, Pd, Pt).6 Closo-In16 and nido-Inu clusters have also been found. Thallium, too, forms Zintl clusters Na2H contains Tlf tetrahedra, while K8T1ii is similar to In, and KT1 contains Tl octahedra.7... 

There is a variety of compounds that have Si bound to transition metals in relatively simple molecules such as Si[Re(CO)5]4 or in clusters such as [Co9(/x8-Si)(CO)21]2 . Germanium, tin, and lead also form clusters such as [Co5Ge(CO)16], Co4Pb(CO)16(PR3)4, and [Fe4Pb(CO)16]2 metallated Zintl ions are found in anions such as [Sn4Cr(CO)5 6]2- and [Ge9(/a1o-Ge)Ni(PPh3)]2. 17 ... 

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. 

Anionic Naked Clusters of Bismuth Zintl Ions... 

If electrons are added into the crystal structure, they lead to the breaking of the Sn-Sn bonds, each atom carrying an unshared electron pair, and ultimately to the formation of isolated anionic clusters with triangular faces (deltahedra), known as Zintl ions (e.g. 1 and 2 see Chapter 1.6). These compounds are diamagnetic and poor conductors. They can be prepared either by reduction of tin with an alkali metal or electrochemically, and are soluble in polar, basic solvents. For example, [Na+]4 [Sng]" " can be prepared from the reaction of tin with sodium in ethylenediamine, or in the presence of a crown ether to associate with the sodium cations. The most common structure is a nine-atom cluster 2. ... 

Negatively charged clusters of some of the p-metals and semimetals are also stable in solutions and can be crystallized from them as ionic molecular compounds. Known, at present, are a number of such ligand-free anionic clusters, called Zintl ions. Some examples are the clusters with general formulas PUy", Eg , Eg , aud Ej where Pn = P, As, Sb and E = Si, Ge, Sn, Pb. This chapter will limit its attention to the synthesis, structure, and functionalization of molecular anionic clusters of tin. Although both nine- and five-atom clusters are known (Figure 2.6.1), the focus will be predominantly on the nine-atom deltahedral clusters Sug and Sn which are the most readily prepared and most extensively studied species. 

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