Electron-atom pair formation, equation

Due to the high rate of reaction observed by Meissner and coworkers it is unlikely that the reaction of OH with DMSO is a direct abstraction of a hydrogen atom. Gilbert and colleagues proposed a sequence of four reactions (equations 20-23) to explain the formation of both CH3 and CH3S02 radicals in the reaction of OH radicals with aqueous DMSO. The reaction mechanism started with addition of OH radical to the sulfur atom [they revised the rate constant of Meissner and coworkers to 7 X 10 M s according to a revision in the hexacyanoferrate(II) standard]. The S atom in sulfoxides is known to be at the center of a pyramidal structure with the free electron pair pointing toward one of the corners which provides an easy access for the electrophilic OH radical. 

Reduction of bulky organohalogermylenes leads to the formation of pentametallic germanium clusters 149 and 150 (Equations (260) and (261), respectively).322 The structure of 149 is shown in Figure 8, and selected structural data are collected in Table 32. The five germanium atoms are held together by six two-center, two-electron bonds, and a lone pair resides on the unsubstituted Ge(5) atom. 

Fig. 16.17. Mechanism of the carbocupration of acetylene (R = H) or terminal alkynes (R H) with a saturated Gilman cuprate. The unsaturated Gilman cuprate I is obtained via the cuprolithiation product E and the resulting carbolithiation product F in several steps—and stereoselectively. Iodolysis of I leads to the formation of the iodoalkenes J with complete retention of configuration. Note The last step but one in this figure does not only afford I, but again the initial Gilman cuprate A B, too. The latter reenters the reaction chain "at the top" so that in the end the entire saturated (and more reactive) initial cuprate is incorporated into the unsaturated (and less reactive) cuprate (I). - Caution The organometallic compounds depicted here contain two-electron, multi-center bonds. Other than in "normal" cases, i.e., those with two-electron, two-center bonds, the lines cannot be automatically equated with the number of electron pairs. This is why only three electron shift arrows can be used to illustrate the reaction process. The fourth red arrow—in boldface— is not an electron shift arrow, but only indicates the site where the lithium atom binds next.

These are called sp hybrid atomic orbitais because they are formed from one s and two p orbitals. The formation, shape, and orientation of the sp hybrids are shown in Figure 6.42. They lie in the x-y plane with an angle of 120 between them. After hybridization, the electron configuration of the atom is B (1s) ( i) ( 2) (A3) Each of the sp hybrids can overlap with a H(ls) orbital to produce a a bond. The wave functions for all bonding pairs would be the same, and they will have the same form as those in Equations 6.34a and 6.34b. The third column of Eigure 6.42 shows the traditional qualitative sketches of the orbital overlap leading to a bonds in BH3, and the fourth column shows the electron density in these bonds as calculated by GVB. Experimentally, BH3 molecules turn out to be unstable and react rapidly to form or other higher com-... 

Equation 3a is important because it involves oxygen-atom transfer to the iodine, which is necessary for the eventual formation of I03. The reaction should be kinetically facile because donation of an electron pair from I" to an... 

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