Lead Zintl ions

Table 4 NMR data for the transition metal derivatives of Lead Zintl Ions ...

Electrochemical formation of Pb(II) complexes by anodic dissolution of lead [83-89] and studies on electrochemical properties of Pb(IV) complexes as well as organo-lead compounds have been reported [90, 91]. Electrogenerated chemiluminescence of Pb(II)-bromide complexes has been described [92]. Reduction of lead to Zintl ions, such as Pbg , has been... 

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 ... 

At very negative potentials neither the tetraalkylammonium ions nor the metallic electrode are inert they combine to form reduced TAA-metals [7]. Tetraalkylammonium (TAA) metals are composed of quaternary ammonium ions, electrons, and a post-transistion metal such as Hg, Pb, Sn, Sb, Bi [5-18] or Pt [19] most of them have the composition R4N" MeJ [13] or R4N" Mc4 [20] and have been described as Zintl ion salts or Zintl phases [21,22]. They have been shown to be useful intermediates in the electrochemical reduction of certain substrates that are reducible with difficulty. On reduction of the quaternary ammonium salt, the initial layer of the metal compound is controlled by a two-dimensional nucleation, whereas the bulk phase is initiated by a three-dimensional nucleation and a growth controlled by the diffusion of R4N from the solution. In some cases (A-methylquinuclidinium (MQ" ) mercury) the catalytic efficiency of the initial layer is greater than that of the bulk phase [18], whereas in other cases (A, A-dimethylpyrrolidinium (DMP" ) lead) the opposite is found [16]. 

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. ... 

Most, if not all, solids containing Zintl ions and sequestered alkali metal ions are infinitely stable in the absence of moisture and oxygen. Since the original report of the solid state structures of (crypt-Na+)2(Pbs ) and (crypt-Na )4(Sn9 ) in 1975, " the synthetic use of crypt has now produced compounds containing Zintl ions of germanium, tin, lead, arsenic, antimony, bismuth and tellurium. " ... 

A review of discrete and condensed homoatomic clusters of germanium, tin, and lead is presented in Section 5.7. These main group cluster compounds are usually called Zintl ions or Zintl phases in recognition of extensive studies of Zintl and coworkers in the 1930s." The science of nanoparticles with conducting and... 

The reaction between a 1,2-ethanediamine solution of K4[Pb9] and a toluene solution of [Pt(PPh3)4] in the presence of crypt-222 leads to the formation of the platinum-centred Zintl ion [Pt Pbi2], the Pb NMR spectrum of which consists of a pseudo-triplet (/207pj, 5p( = 3440 Hz). 

The lithiation (using BuLi) of Ph2SbH in THF leads to Ph2SbLi(THF)3 which can be isolated as a crystalline solid. In contrast, lithiation of PhSbH2 in Me2NCH2CH2NMe2 results in Sb-Sb bond formation and the [Sb7] ion. This provides a convenient method of preparing this Zintl ion (see Section 15.6). 

This simple Zintl-Klemm concept has some obvious limitations as illustrated by differences in the two MTl intermetallics (M = Na [27] and Cs [28]). Thus complete electron transfer from M to T1 leads to M TF, where the TF anion with four valence electrons is isoelectronic with a neutral group 14 atom and four bonds are needed to attain the octet configuration. Hence, the TF anion should form structures similar to allotropes of carbon or heavier group 14 elements. Indeed, NaTl has a stuffed diamond structure [27] with internal Na ions and an anionic (TF)oo lattice similar to diamond. However, the TF anions in [CsTl] form tetrago-nally compressed octahedra [28] unlike any structures of the allotropes of carbon or its heavier congeners. 

---