Phosphorus boron-carbon bonds

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. 

During the introduction of this review, reference was made to the classical rule of the double bond. The theory, which in its original predictions supports the exceptional position for the elements boron, carbon, nitrogen, and oxygen, has lost its validity and needs modifications, as can be seen from the erratic increase in the numbers of compounds that contradict the rule that have been discovered within the last 12 years. These compounds are not found only as low-valent phosphorus-carbon species, but also increasingly as heteronuclear and even homonuclear molecules built up by heavier elements of the fourth to sixth main groups, such as Si, Ge, As, Sb, S, and Se. 

The Miedema modeP describes bonding in intermetallic, ordered compounds of metallic elements. In addition to the metallic elements the model also includes the elements hydrogen, boron, carbon, nitrogen, silicon, and phosphorus in their metallic... 

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... 

It is found that multiple bonds are often formed by elements in the first row of the periodic table (boron, carbon, nitrogen, oxygen), and less often by the heavier elements. For example, the nitrogen molecule, N.>, has the structure N=N , whereas the phosphorus molecule, P4, contains six bent single bonds. 

In this book we are concerned with the properties of compounds which contain metal—carbon bonds. Traditionally organometallic chemistry includes the carbon compounds of the metalloids boron, silicon and arsenic, but excludes those of phosphorus and of other more electronegative elements. Metal carbonyls are discussed, but not cyanides or carbides, which are more usefully considered in conjunction with inorganic rather than organometallic compounds. 

The PdCl2(CH3CN)2-catalyzed phosphination and borylation of aryl halides have also emerged as powerful methods for carbon-phosphorus and carbon-boron bond formation, respectively. 

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