Solid state structures halogens

In a series of papers Reed and colleagues present the solid state structures of a series of simple trialkyl-substituted silyl cations with halogenated carborane anions... 

The nitryl halides (C2 symmetry) are planar in analogy to the isoelectronic COs. The gas phase and solid-state structures for CINO2 both show covalently bound molecules (see Table 40). In contrast to the nitrosyl hahdes, the halogen-nitrogen bond distances in the gas phase and in the solid state are similar. The nitryl halides NO2F and NO2CI are the mixed anhydrides of nitric acid and hydrofluoric or hydrochloric acid, respectively. 

In solid Bep2, a complex network is formed with a Be atom coordination number of 4 (see Figure 3.7). BeCl2 dimerizes to a 3-coordinate structure in the vapor phase, but the linear monomer is formed at high temperatures. This monomeric structure is unstable due to the electronic deficiency at Be in the dimer and the network formed in the solid-state, the halogen atoms share lone pairs with the Be atom in an attempt to fill beryllium s valence shell. The monomer is still frequently drawn as a singly bonded structure, with only four electrons around the beryllium and the ability to accept lone pairs of other molecules to relieve its electronic deficiency (Lewis acid behavior, discussed in Chapter 6). 

The pyrogallol[4]arenes typically separate from complex reaction mixtures. As they are crystalline, a number of solid-state structures have been reported from a number of laboratories. The majority of these structures involve Unear chains, although some are unsaturated or terminated by a halogen or alcohol function. Relatively little information was available concerning branched chain pyrogallol[4]arenes. We anticipated that, like the Unear-chained counterparts, the pyrogallol[4]arene derivatives would crystallize either in the capsular or bilayer form. 

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