Boron silicon-phosphorus bonds

Element-element bonds, addition to G-G multiple bonds arsenic—selenium bonds, 10, 782 boron—boron bonds, 10, 727 boron—sulfur bonds, 10, 778 B-S and B-Ge bonds, 10, 758 chalcogen—chalcogen additions, 10, 752 germanium—germanium bonds, 10, 747 germanium-tin bonds, 10, 780 overview, 10, 725-787 phosphorus—phosphorus bonds, 10, 751 phosphorus—selenium bonds, 10, 782 phosphorus-sulfur bonds, 10, 781 Se-Si and Se-Ge bonds, 10, 779 silicon-germanium bonds, 10, 770 silicon-phosphorus bonds, 10, 780 silicon-silicon bonds, 10, 734 silicon-sulfur bonds, 10, 779 silicon-tin bonds, 10, 770 tin-boron bonds, 10, 767 tin-tin bonds, 10, 748... 

The comparison of the bond energies in boron, silicon, phosphorus and arsenic atoms with that of carbon atoms supports this idea (Table 2). 

This chapter deals with the formation of new C—C bonds by alkylation of sp -hybridized carbanions stabilized by a range of heteroatoms, including oxygen, boron, silicon, phosphorus and the halogens. The properties of the same carbanions with additional stabilization provided by an adjacent double bond are also discussed. 

Non-metallic stractures of boron, silicon, phosphorus, and bromine can be bonded to phenolics. In most cases, these resins show an improved thermal stability in comparison to the nonmodified ones [1], Boron modified phenolics are prepared from aryl borates that are synthesized from phenol and boric acid (Scheme 26). The aryl borates react with methanal or 1,3,5-trioxane as shown in Scheme 26 to give boron modified prepolymers [167,168],... 

Organometallic compounds are those in which there is a metal-carbon bond. According to this definition, in the case of transition metals, this group of compounds includes not only metal carbonyls, olefin complexes, cyclopentadienyl, and other 7r-complexes, but also cyanide and fulminate compounds. Certain difficulties arise in defining the metal of the main group elements. Usually, organometallic compounds are comprised not only of compounds of typical metals, but also of metalloids such as boron, silicon, phosphorus, arsenic, selenium, etc. In compounds of metals as well as in those of metalloids, the bond is generally polarized as follows C. Consequently, the... 

The methods available for synthesis have advanced dramatically in the past half-century. Improvements have been made in selectivity of conditions, versatility of transformations, stereochemical control, and the efficiency of synthetic processes. The range of available reagents has expanded. Many reactions involve compounds of boron, silicon, sulfur, selenium, phosphorus, and tin. Catalysis, particularly by transition metal complexes, has also become a key part of organic synthesis. The mechanisms of catalytic reactions are characterized by catalytic cycles and require an understanding not only of the ultimate bond-forming and bond-breaking steps, but also of the mechanism for regeneration of the active catalytic species and the effect of products, by-products, and other reaction components in the catalytic cycle. 

There are other elements (such as boron, silicon, and phosphorus) which can form chains of atoms bonded to one another. Carbon is unique because it not only forms strong carbon-carbon bonds but also because these bonds remain strong when the carbon atoms are bonded with other elements. Carbon compounds are stable and relatively unreactive chemically. This is not true of the compounds of other chain-forming atoms. 

But carbon is not unique in forming bonds to itself because other elements such as boron, silicon, and phosphorus form strong bonds in the elementary state. The uniqueness of carbon stems more from the fact that it forms strong carbon-carbon bonds that also are strong when in combination with other elements. For example, the combination of hydrogen with carbon affords a remarkable variety of carbon hydrides, or hydrocarbons as they usually are called. In contrast, none of the other second-row elements except boron gives a very extensive system of stable hydrides, and most of the boron hydrides are much more reactive than hydrocarbons, especially to water and air. 

Homonuclear carbonyl dimers, palladium complexes, 8, 206 Homonuclear element-element bonds, addition to C-C multiple bonds boron-boron bonds, 10, 727 chalcogen-chalcogen additions, 10, 752 germanium-germanium bonds, 10, 747 phosphorus-phosphorus bonds, 10, 751 silicon—silicon bonds, 10, 734 tin—tin bonds, 10, 748... 

Different elective affinity of elements as compared to carbon. Electropositive elements (Si, B, AI, P) have a considerably larger affinity to electronegative elements than carbon. In other words, silicon, boron, aluminum, phosphorus and other elements form weaker bonds with electropositive elements (H, Si, B, Al, As, Sb, Bi, etc.), and stronger bonds with electronegative elements (O, N, Cl, Br, F, etc.) than carbon. 

We are investigating a series of reactions of aminopyridines and aminopyrimidines and main group compounds. These heterocycles can form adducts with both kinds of nitrogen atoms pyridinic or anilinic. Bonding of several aminopyridines to heteroatoms such as boron, silicon, or phosphorus gives polyfunctional molecules rich in lone pairs and therefore candidates to be used as ligands. 

The direct linking of like atoms, such an essential feature of carbon chemistry, occurs to only a limited extent with other elements. Metal-metal bonds are not uncommon but they are always weak examples are found in the polynuclear carbonyls (p. 306) and compounds such as SugRg and PbgRfi (R = alkyl). Among the other non-metals catenation is displayed by boron, silicon, germanium, phosphorus and sulphur none of the substances... 

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