Interhalogens structures

Typical examples of linear (or nearly linear) triatomic polyhalides are in Table 17.15 the structures are characterized by considerable variability of interatomic distances and these distances are individually always substantially greater than for the corresponding diatomic interhalogen (p. 825). Note also that for... 

Sei f-Test 2.4A Write the Lewis structure for the interhalogen compound chlorine... 

Interhalogen compounds are compounds of two different halogens that have, with few exceptions, the general formula XX . Examples include BrCI, C1F, and IF5. Use I ewis structures to explain why n is always an odd number. 

Second only to sulfur-based systems, nitrogen complexes are relatively well represented in the structural literature with 41 complexes reported. Of these, 25 are with I2 as the electron acceptor, 11 are with the interhalogen IC1, three are with Br2, and two are with IBr. As expected, in every case the halogen bond forms between the nitrogen and the softest halogen atom, i.e., iodine, in all of the complexes except those with dibromine. Most N I2 complexes, and all N Br2, N IBr, and N IC1 complexes are simple adducts, mode A. Exceptions for the diiodine complexes include bridging mode (B) observed for diazines, such as pyrazine [86], tetramethylpyrazine [86], phenazine, and quinoxaline [87], and for 9-chloroacridine [89] and the 1 1 complex of diiodine with hexamethylenetetramine [144] and amphoteric bridging mode (BA) observed for 2,2 -bipyridine [85], acridine [89], 9-chloroacridine [89], and 2,3,5,6-tetra-2/-pyridylpyrazine [91]. The occurrence of both B and BA complexes with 9-chloroacridine, and of B and A complexes and an... 

By analogy to the carbon systems that contain three atoms, describe the structure of interhalogen species (see Chapter 15) such as I3 . Assuming that only p orbitals are used, describe the bonding in this species. 

Only three of the possible XX 3 interhalogens (C1F3, BrF3, and IF3, which is stable only at low temperature) are important. The structure of BrF3 can be shown as... 

Structures of Interhalogen Compounds and Polyhalides E. H. Wiebenga, E. E. Havinga, and K. H. Boswijk... 

Interhalogen bonds are accompanied by very low LUMOs see Figure 4.5) and thus can function as good a electron acceptors. The donor-acceptor complexes between ammonia and F2, CI2, and C1F have been investigated theoretically [93] and found to have linear structures, as expected on the basis of the above discussion. 

The halogen pentafluorides and the [XeF5]+ cation have a square pyramidal configuration and any weak secondary bonds are found below the base of the pyramid and situated to avoid the axial, lone pair position. These contacts are much more significant for the xenon compounds than for the interhalogens, where they are so weak as to be virtually indistinguishable from normal intermolecular contacts, as seen in the structure of IF5.40... 

At room temperature pyridines react reversibly with halogens and interhalogens, e.g. IC1, to give unstable adducts, which behave as mild halogenating agents. X-Ray diffraction studies of the pyridine-iodine complex have given its structure (73). 

The interhalogen compounds obey the expectations based on the VSEPR theory, and typical structures are giver in Chapter 6. Ore compound not included there is the dimeric iodine trichloride, in which the iodine atom of the monomeric species appears to act as a Lewis acid and accept an additional pair of electrons from a chlorine atom (Fig. 17.5). 

Structures of some interhalogen ions. The number of electrons in the valence shell of the central atom is given for each ion. 

The PES studies of alkyl dihalides have been mostly concerned with the transfer of interhalogen interactions through the unbranched alkane chain98 99. The halogen lone-pair ionizations are easily identified, and provide a ready probe for these studies. Measurements of the spin-orbit (SO) splitting, vibrational fine structure and lone-pair bandwidths produced the following conclusions ... 

The structures of the interhalogens having the formula XX are polar diatomic molecules. 

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