Metalloid synthesis

A quite surprising development, even to experienced workers in elemental-fluorine chemistry, has been the synthesis of trifluoromethyl organometallic compounds by direct fluorination of metal alkyls (25). Even more surprising is the fact that, for certain metal and metalloid systems, such as the reaction of elemental fluorine with tetramethyl-germane, this t5rpe of low-temperature synthesis is a practical method 26) for the laboratory preparation of the perfluoro analog. 

This review concerns in the first part the works published during the last three years on the synthesis and reactivity of stabilized ylides C-substituted by electron-withdrawing groups (COR, CO2R, CN, etc.). The second part deals with the works published in the same period on the chemistry of phosphorus ylides mainly C-substituted by heteroatoms of groups 1-16 (metals, metalloids and nonmetal elements Li, Ba, Ca, Ti, Zr, Nb, Mo, Re, Fe, Ru, Rh, Pd, Pt, Au, Zn, Hg, B, Si, Sn, N, P, As, Sb, O, S, Te). 

There is concern over the toxicity of a nnmber of metals and metalloids, and their oxyanions. As for antibiotics, the genes for resistance are often plasmid-bome. There are several mechanisms that may operate—redaction, methylation, efflnx, and the synthesis of metal-binding metallothioneins. The following text illustrates aspects of these mechanisms. 

There are distinct structural types of organic compounds containing metals and metalloids. The first contain covalent carbon-metal bonds and are strictly organometallic compounds, for example, the alkylated compounds of Hg, Sn and Pb, and of Li, Mg, and A1 (and formerly Hg), which have been extensively used in laboratory organic synthesis, and A1(C2H5)3 that is a component of the... 

The more molecular character of 9 in comparison to 8-gallium is responsible for a decrease of the bond lengths by about 25 pm. These results prove that 9, considering its synthesis as well as the electronic structure, has to be classified in between polyhedral gallium clusters such as the square antiprismatic cluster GajjiCnHcih2- 72 and metalloid clusters. 

The clusters described so far have in common, that the number of metal atoms is less or equal than the number of substituents. However, there is a still growing number of both neutral and anionic clusters in which the number of metal atoms is larger than the number of substituents. As a consequence, these metal-rich clusters contain naked metal centers which are only bonded to other metal centers. Schnockel referred these ones to as metalloid clusters. Several metalloid A1 and Ga clusters were prepared by standard salt elimination reactions using metastable solutions of metal subhalides MX (M = Al, Ga X = Cl, Br) as well as solutions of Gal. Since the metal subhalides were found to play the key role for the successful synthesis of this particular class of compounds, they will be discussed first. (For excellent review articles see Refs 273 and 274.)... 

The development of the synthesis concept described here for metalloid clusters should ultimately be capable of extension to element combinations and therefore molecular nanostructured alloys, as several results on metalloid SiAl and SiGa clusters have shown [114, 88, respectively]. Such mixed clusters resemble the Zintl-type compounds that are under intense investigation by Corbett et al. [115, 124-126],... 

One path of research resulting from the discovery of ferrocene has been concerned with the synthesis and structural elucidation of cyclopentadienyl derivatives of other metals and metalloids. At the present time, over 60 chemical elements have been found to form one or more cyclopentadienyl compounds. This topic has recently been reviewed by the present author as well as by others (17, 83, 125). 

M. F. Lappert, P. P. Power, A. R. Sanger and R. C. Srivastava, Metal and Metalloid Amides Synthesis, Structures, and Physical and Chemical Properties Horwood-Wiley Chichester, 1980. 

G. A. Tolstikov and U. M. Dzhemilev, Khim. Geterotsikl. Soedin., 1980, 147-163. Metalloid Heterocycles for Organic Synthesis A. Shanzer, Isr. J. Chem., 1979,18,354-358. Synthesis of Heterocycles via Organometallic Complexes M. Mori and Y. Ban, Kagaku no Ryoiki, Zokan, 1979, 97-121. 

These rings, their synthesis, structure, reactions and physical properties are surveyed as part of the annual reports of the organometallic chemistry of the Group IV metalloids [Pg.574]

Alkaline earth-containing ternary nitrides make up the second largest group of ternary phases. Because the alkaline earth metals form stable binary nitrides, most alkaline earth containing ternary nitrides have been synthesized by the reaction of a binary nitride with a metal or by the reaction of two binary nitrides. This synthesis has resulted in a number of new ternary nitrides with a variety of structures. For example, the reaction of calcium nitride with Group 14 or 15 metals or metalloids forms a series of structurally related ternary nitrides with the anti-perovskite type structure. In Ca3MN (M = P, As, Sb, Bi, Ge, Sn, Pb) (Figure 8.5) the... 

Sodium has been widely used in the synthesis of various organo-metals and organo-metalloids, by causing the halides of the elements to react with organic halogen compounds. The following are examples of this type of reaction ... 

Throughout his whole career, Lappert has been a firm supporter of basic research driven purely by intellectual curiosity, rather than by current fashions of applying chemistry to its several sister disciplines. He mentored well over 100 Ph.D. students, and with his coworkers published nearly 800 papers and reviews on various aspects of inorganic and organometallic chemistry. The emphasis of his work has been on the synthesis and the characterization of compounds in novel or unusual oxidation states and/or geometries. Most of the results relate to molecular chemistry of the metals and metalloids, a characterization that allows inclusion of the extensive contributions to the chemistry of amide... 

Among possible methods available to accomplish the synthesis of an alkyl- or aryl-metal or -metalloid compound, organo-... 

In a recent communication, the cluster [SnisRg] has been shown to have the structure below (Brynda et al., 2006). Described as a metalloid cluster and an advance in the quest for a bottoms up synthesis of Sn nanoparticles, the electronic structure of this compound in terms of electron counting was not addressed. Do so. 

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