As-X bonds

The broken bonds (boldface = dissociated recommended data reference in parentheses) Methods (reference in  

The broken bonds (boldface=dissociated atom or group) BDEs (boldface = recommended data reference in parentheses) kcal / mol kj /mol Methods (reference in parentheses) References 

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As—C Bonds Formed by Addition Reactions a. Addition of Olefins and Acetylenes to As—X Bonds (i) X = Cl. Acetylene and arsenic trichloride react in the presence of aluminum trichloride to give a mixture known as "Lewisite 11,12,179). 

The P-X bond is generally less stable than the P-C bond, and compounds containing P-X bonds are almost aU unstable to air and water. Their thermal stabilities generally decrease with increasing atomic weight of X. The corresponding compounds with As-X bonds are in most cases known. 

Sodium carbonylmetallates similarly react with compounds containing P-X and As-X bonds in hydrocarbon solvents with formation of NaX as an insoluble by-product, 5- 7 gq. 5.20 and 5.21 ... 

We ai e free to pick a tefei ence poitit of energy once, but otily otice, for each system, l,et us choose the reference point t.. We have obtained the energy eigenvalues of the x bond in ethylene as one [f greater than y. 011)11 bunding) and one p lower than y ( bunding) (Fig, 6-3),... 

Two of the most severe limitations of the harmonie oseillator model, the laek of anharmonieity (i.e., non-uniform energy level spaeings) and laek of bond dissoeiation, result from the quadratie nature of its potential. By introdueing model potentials that allow for proper bond dissoeiation (i.e., that do not inerease without bound as x=>°o), the major shorteomings of the harmonie oseillator pieture ean be overeome. The so-ealled Morse potential (see the figure below)... 

The group moment always includes the C—X bond. When the group is attached to an aromatic system, the moment contains the contributions through resonance of those polar structures postulated as arising through charge shifts around the ring. 

Fatty acids are represented as x y, where AT is the carbon chain length andjy is the number of double bonds. ... 

Cycloadditions including a cyclic S atom and an exocyclic C=X bond are known in the dithiazole series, e.g. as shown in Scheme 44. 

Synthesis of heterocycles by forming C—X bonds by radical reactions is not a generally applicable method, and seems not to be useful for making small rings. However, the attack of thiol radicals on double bonds can be a practical synthetic route, such as in the conversion of 1-hexene-7-thiol to thiepane (Section 5.17.3.3.1). 

Dynamic SIMS is used to measure elemental impurities in a wide variety of materials, but is almost new used to provide chemical bonding and molecular information because of the destructive nature of the technique. Molecular identihcation or measurement of the chemical bonds present in the sample is better performed using analytical techniques, such as X-Ray Photoelectron Spectrometry (XPS), Infrared (IR) Spectroscopy, or Static SIMS. 

The anomeric effect is also present in acyclic systems and stabilizes conformations that allow antiperiplanar (ap) alignment of the C—X bond with a lone-pair orbital of the heteroatom. Anomeric effects are prominent in determining the conformation of acetals and a-alkoxyamines, as well as a-haloethers. MO calculations (4-3IG) have found 4kcal/mol as the difference between the two conformations shown below for methoxy-methyl chloride. ... 

These effects are attributed to differences in the c-donor character of the C—C bonds as a result of substitution. Electron-attracting groups diminish the donor capacity and promote syn addition. An alternative explanation invokes a direct electrostatic effect arising from the C-X bond dipole. 

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