Anions, Zintl

Many liquid alloys, in particular, the alkali-group IV alloys, exhibit (Zintl) anion clustering and show strong effects of compound formation. A typical example of such Zintl systems are sodium-tin alloys. In the solid NaSn crystal the Zintl anions Sn appear [1]. An interesting question is the stability of these anions in the liquid. Furthermore, the electrical conductivity of these alloys shows a strong dependence on composition [2] For the limiting (sodium-rich or tin-rich) cases a metallic (small) conductivity appears, but for the nearly equimolar compositions a semi-metallic behavior - with a considerably smaller conductivity - is observed. 

From the obtained trajectories the following structural and electronic properties were extracted (i) structure factors, (ii) stability of Sn complexes, in particular, the Zintl anions, and (iii) the electrical conductivities - which yield answers to the questions mentioned in the first paragraph. 

In a previous paper the Car-Parrinello (CP) technique was applied to the equimolar NaSn alloy [6]. In a further publication [7] we extended these investigations to a wide range of compositions ranging from 20% up to 80% of sodium and discussed the static structure factors and the behaviour of the Zintl anions (Sn ) in the molten alloys. 

An essential result of the simulations is that the Zintl anions Sn for the equimolar case do not survive in the liquid. They form (dynamical) networks. For the liquid with 80% of sodium, the suggested octet compounds SnNa4 do not exist, and only isolated tin atoms or tin dimers appear. 

In addition, for the sodium-antimony alloy, where the Zintl anions are Sb spiral chains, ab initio MD simulations are in progress. 

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

Draw valence bond formulas for the following ZiNTL 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... 

The same rules may be applied to the Zintl anion Bobserved in compounds such as CaB6 and corresponding to a framework of corner-sharing boron octahedra as described in the following 4.4.4.7. 

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

The Sn6[M(CO)5]6 clusters (M = Cr, Mo, W) [51] are not prepared from Zintl anions, but the Siig octahedral cores can be viewed as a closo 2n+2 member of the deltahedral Zintl anion series and are similar to the cZoso-trigonal bipyramidal Sns ion. The Sn chemical shifts of the Sn6[M(CO)5]6 complexes are in the range 198-561 ppm and are somewhat downfield of the anionic Zintl clusters. Large one-bond Sn-Sn couplings of 1,800 Hz are suggestive of nonfluxional compounds. 

Birchall T, Bums RC, Devereux LA et al (1985) A Sn-119 mossbauer study of some nonclassically (cluster) and classically bonded zintl anions. Inorg Chem 24 890-894... 

Relationships Between Soluble Zintl Anions, Ligand-Stabilized Cage Compounds, and Intermetalloid Clusters of Tetrel (Si-Pb) and Pentel (P-Bi) Elements... 

Keywords Cage compound Cluster Intermetalloid Pentel Structure Tetrel Zintl anion... 

Structures of Soluble Homoatomic Zintl Anions of Group 14 and 15 Elements.95... 

Zintl Anions, Ligand-Stabilized Cage Compounds, and Intermetalloid Clusters of the... 

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