C-Cl Bond length

The IRC calculation confirms that the preceding transition structure does indeed connect these two minima. The C-Cl bond length increases as it proceeds in the forward direction along the reaction path, and this bond decreases in length in the reverse direction (naturally, the C-F bond length changes in the complementary manner). 

Molecular orbital calculations made on t-BuCl show that the C—Cl distance in the intimate ion pair is 2.9 A and the onset of the solvent-separated ion pair takes place at 5.5 A (cf. the C—Cl bond length of 1.8 A). 

FIGURE 3.21. Gas-phase potential energy surfaces for the 4-cyanochlorobenzene anion radical as a function of the C-Cl bond length (r) and the bending angle (0). R, reactant system TS, transition state. Adapted from Figure 4 of reference 32, with permission from the American Chemical Society. 

Furthermore, the axial C—X bonds are unusually long in comparison with aliphatic C-X bonds342. An especially interesting observation is the difference between the axial and equatorial C—Cl bond lengths of the system shown below. This observation is in accord with greater n< —u[Pg.177]

Figure 6.12 The anti-SN2 reaction of chloride with allyl chloride. While RHF theory does well with the reactant/product geometries, it significantly overestimates the C-Cl bond lengths in the C2 symmetric TS structure based on calculations at more reliable levels of theory...

C(sp)—Cl bond distances in various acetylenes (Table 28) have a remarkably constant value of ca 163.5 pm and variations due to electron-donating (Me, t-Bu, SiH3) or electron-withdrawing substituents (F, Cl, CN) at the opposite carbon are smaller than the experimental uncertainties. ED and MW for chlorobromoacetylene result in rather different ra and r0 values for the C—Cl bond length and this discrepancy may be due to large-amplitude bending vibration of this linear molecule. A similar, but smaller difference between ra and rs values occurs for chlorocyanoacetylene. The rs value for chlorine cyanide is also in line with the results for the acetylenes. 

Chlorinated dibenzo-p-dioxines are of great interest because of their toxicity which depends strongly on the degree and on the position of chlorination. C—Cl bond lengths of... 

Related to this topic is the exhaustive discussion of the relationship between C-Cl bond length and 35C1NQR frequencies of organochlorine compounds29. A number of the investigations of the effect on halogen NQR frequencies in particular systems are discussed below. 

Similarly to halogenoacetamide, R2P(0)CH2C1 can capture an electron and form an anion which, in the case of Ph2P(0)CH2Cl259, was trapped in a single-crystal matrix at 3 K. This anion is of the cr type with an increase in the C—Cl bond length of approximately 0.4 A. 

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