Chloride ion, bonding

Figure 4.7 When solutions of silver nitrate and sodium chloride are mixed, the silver and chloride ions bond together forming a solid with an ionic lattice.

The formation of [PdCl2(C2H4)2] in the presence of Cl ions does not occur, because chloride ions bond more strongly to palladium. However, compounds containing one or two ethylene molecules are formed in aqueous solutions of palladium... 

The reaction of an organic halide with a metal is an oxidation-reduction in which the metal is the reducing agent. As shown in the fohowing equahons for the reactions of methyl chloride with lithium and with magnesium, a single-electron transfer from the metal converts methyl chloride to a radical anion, which then dissociates to a methyl radical and chloride ion. Bond formahon between methyl radical and a metal species ( Li or Mg" ) follows. 

The active center in Figure 2.5 is shown as a titaniiun atom with an octahedral configuration with three chloride atoms in the equatorial position and one axial chloride atom and one axial alkyl group (R). Importantly, this octahedral configuration is (a) coordinately xmsaturated (exhibits a vacant coordination site in an equatorial site), which is needed in order for the ethylene molecule to coordinate into the first coordination sphere around the titanium atom, and (b) possesses a Ti-carbon bond formed from the exchange of an alkyl group from the aluminum alkyl and a chloride ion bonded to the titanium. 

The Lewis bases that react with electrophiles are called nucleophiles ( nucleus seek ers ) They have an unshared electron pair that they can use m covalent bond formation The nucleophile m Step 3 of Figure 4 6 is chloride ion... 

The transition state for this step involves partial bond formation between tert butyl cation and chloride ion... 

Addition begins m the usual way by protonation of the double bond to give m this case a secondary carbocation This carbocation can be captured by chloride to give 2 chloro 3 methylbutane (40%) or it can rearrange by way of a hydride shift to give a tertiary carbocation The tertiary carbocation reacts with chloride ion to give 2 chloro 2 methylbutane (60%)... 

FIGURE 8 4 Solvation of a chloride ion by hydrogen bonding with water... 

The fluoride ion is the least polarizable anion. It is small, having a diameter of 0.136 nm, 0.045 nm smaller than the chloride ion. The isoelectronic E and ions are the only anions of comparable size to many cations. These anions are about the same size as K" and Ba " and smaller than Rb" and Cs". The small size of E allows for high coordination numbers and leads to different crystal forms and solubiUties, and higher bond energies than are evidenced by the other haUdes. Bonds between fluorine and other elements are strong whereas the fluorine—fluorine bond is much weaker, 158.8 kj/mol (37.95 kcal/mol), than the chlorine—chlorine bond which is 242.58 kJ/mol (57.98 kcal/mol). This bond weakness relative to the second-row elements is also seen ia 0-0 and N—N single bonds and results from electronic repulsion. 

Although it is conceivable that the nucleophilic chloride ion initiates the attack, much experience supports the classification of (1-4) as an electrophilic reaction. Of course, if is the attacking electrophile, the double bond must be functioning as a nucleophile.] Equation (1-5) shows an AdN reaction. 

Galvanised steel provides increased corrosion resistance in carbonated concrete. In concrete with more than 0.4% chloride ion with respect to the cement content, there is an increased risk of corrosion and at high chloride contents the rate of corrosion approaches that of plain carbon steel. In test conditions the rate of corrosion is greater in the presence of sodium chloride than calcium chloride. Fusion-bonded epoxy-coated steel performs well in chloride-contaminated concrete up to about 3.9% chloride ion in content. 

The formation of 120 can be explained by attack of chloride ion at C-6 (rather than the more hindred endo side at C-3) as depicted in the intermediate 126, with concomitant migration of the ketal function to the 3,5-position. This procedure provides a convenient route to 6-substituted D-glucose derivatives from the readily accessible 49. Since rotation about the C-5—0 bond is required for the migration of the ketal, the reaction most likely is not of a concerted nature and may proceed via 126a-126b. 

The ionic model, the description of bonding in terms of ions, is particularly appropriate for describing binary compounds formed from a metallic element, especially an s-block metal, and a nonmetallic element. An ionic solid is an assembly of cations and anions stacked together in a regular array. In sodium chloride, sodium ions alternate with chloride ions, and large numbers of oppositely charged ions are lined up in all three dimensions (Fig. 2.1). Ionic solids are examples of crystalline... 

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