Electrons lone pairs and

It has long been known that iodine dissolves in solvents possessing electron lone pairs and that the colors of these solutions are related to the solvent s basicity. Explaining this simple observation has required decades of work and has consistently required the application of the most sophisticated experimental tools available. The observation has also continually challenged theories of bonding, and even today taxes the capabilities of the fastest computers in efforts to provide accurate descriptions of its origin. 

It is well known that the octet rule explains most of the chemical bonding of typical elements. Sulfur has, however, a variety of valences, as in such molecules as SF2, SF4 and SF5. As the SF2 molecule has two electron-lone-pairs and two covalent bonds, it satisfies the octet rule. While the valence shell of the SF4 molecule consists of decet electrons the sulfur atom of the SF6 molecule is surrounded by dodecet electrons. Therefore sulfur compounds do not always follow the octet rule. It has been said that the sulfur 3d orbital plays an important role in chemical bonding, and many researches have tried to clarify the nature of sulfur chemical bonding. 

These heterocalixarenes possessing unusually crowded cavities with 3 or 4 nitrogen electron lone pairs and having all sp carbons are expected to be essentially planar. But in its X-ray structure, 89 is distinctly non-planar, due predominantly to lone pair-lone pair repulsions. The distortion from planarity leads to a conformation in which two lone pairs tip out of plane on one side of the molecule and the third tips in... 

Table 1.8 shows Lewis structures, molecular formulas, and names for several compounds. The number of valence electrons each molecule contains is shown in parentheses. Notice in these molecules that each hydrogen is surrounded by two valence electrons and that each carbon, nitrogen, oxygen, and chlorine is surrounded by eight valence electrons. Furthermore, each carbon has four bonds, nitrogen has three bonds and one unshared pair of electrons, oxygen has two bonds and two unshared pairs of electrons (lone pairs), and chlorine (and other halogens) has one bond and three unshared pairs of electrons. 

Forgeron el calculated one-bond P, P indirect nuclear spin-spin coupling tensors, /( P, P), using nonrelativistic DFT and relativistic ZORA DFT methods. Thousands of solution and solid-state P NMR studies have been carried out, and many one-bond P, P isotropic SSCCs, V( P, P)iso, have been measured." The dependence of /( P, P)wo on parameters such as oxidation state, coordination number, substituent electronegativity, the presence or absence of localized electron lone pairs, and stereochemistry is somewhat known, and values of P)wo may be... 

Like the carbon atom in methane and the nitrogen atom in methylamine, the oxygen atom in methanol (methyl alcohol) and many other organic mole-cnles can he described as sp -hybridized. The C-O-H bond angle in methanol is 108.5°, very close to the 109.5° tetrahedral angle. Two of the fonr sp hybrid orbitals on oxygen are occnpied by nonhonding electron lone pairs, and two are used to form bonds. 

In terms of its structure, it is skewed with a dihedral angle of 111.5° (gas phase), which is a balance between maximizing bonding interactions and minimizing repulsion between the electron lone pairs and the O-H bond pairs. 

If the dye ligands contain their own metal centers, they are able to offer both electron lone pairs and Lewis acidic sites for the self-assembly process. Once the orientation between the ligand and the metal is appropriate, the intermolecular complementary coordination in a head-to-tail manner might lead to macrocyclic architectures. Indeed, quite a few supramolecular macrocycles were produced from metalloporphyrin derivatives through the metal-directed self-cycHzation approach. 

A salt MX dissolves in a polymer matrix as it does in a liquid electrolyte to ionize and produce cations M+, anions X, and neutral ion pairs [MX]°. The neutral ion pair can combine further with a cation or an anion to form a triple ion [M2X]+ or [MX2]". The formation of neutral ion pairs [MX]° leads to a decrease in the concentration of carriers. The movement of the triple ion [M2X]+ or [MX2] is sluggish due to its size, and the ionic conductivity decreases due to the existence of these triple ions. Functional oxygen-containing groups in the chain segments have electron lone pairs, and the lithium ion has unoccupied orbitals (2s), so that the Li+ ion can form coordination structures with oxygen... 

It was originally proposed that the value of 107 Hz for J( 0-H) in H30 was consistent with a planar geometry, but this view has since been corrected (the oxygen still retains an electron lone pair, and the ion is pyramidal) despite its ready acceptance. The pattern of Ru satellites (six lines) in the 0 spectrum of RUO4 demonstrated that the former nucleus has spin 5/2. 

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