Homoatomic Zintl anions

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

Fig. 4.66. Structures of some homoatomic Zintl anions established by single crystal X-ray diffraction determinations (a) SnJ", (b) Sn ", (c) Ge ", (d) Pb " (e) BiJ", (f) Sb ". Reproduced with permission from Corbett JD (1985) Chem. Rev. 85 383...

There are a number of compounds containing homoatomic bonds that fall outside the formal oxidation state III or V classification, e.g., Zintl anions and homoatomic cations of Sb or Bi, but these have little or no coordination chemistry. 

An elegant access to larger cluster units is to make use of preformed smaller clusters as they occur, e.g., in Zintl phases [8, 9]. The phase KSi (or K4Si4) contains homoatomic Si4 tetrahedra, and thus a salt-like formulation (Na )4[Si4]" with a formal electron transfer is appropriate (Fig. 1) [10]. Such homoatomic anionic building blocks occur in binary or ternary intermetallic phases A E and A Pn j with A being an alkali and alkaline-earth metal, and E = Si-Pb and Pn = P-Bi. These phases are generally available in good quantities, and - since a few members... 

The occurrence of homoatomic anions [En] of the elements of groups IV (C, Si, Ge, Sn, Pb) and V (P, As, Sb, Bi) as constituents of Zintl phases is well knownJ Despite numerous attempts, just a few of the En clusters have been isolated as uncharged molecules E Rx from the Zintl phases by reaction with suitable agents such as alkyl chlorides. 

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