Disorder in the crystals of trans-4-fluoroazoxybenzene. Synthesis, spectral properties, crystal structures and DFT calculations

trans-Diphenyldiazene oxide

“…In both complexes, azoxybenzene is found in an almost planar conformation, the dihedral angle between phenyl rings being 13.2 and 7.4°, respectively. The same conformation has been observed in derivatives of (I) including a parasubstituted phenyl ring (Ejsmont et al, 2000, 2002, 2004, 2005Domański et al, 2001. Non-planar conformations have been observed e.g.…”

“…Two coordination complexes including the title molecule have been structurally characterized (Bassi & Scordamaglia, 1975;Cambie et al, 1996). For structures of para-substituted azoxybenzenes, see: Ejsmont et al (2000Ejsmont et al ( , 2002Ejsmont et al ( , 2004Ejsmont et al ( , 2005; Domań ski et al (2001). Data collection: XSCANS (Siemens, 1999); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 1998); program(s) used to refine structure: SHELXTL-Plus; molecular graphics: Mercury (Macrae et al, 2006); software used to prepare material for publication: SHELXTL-Plus.…”

Evaluation of the role of disordered organic fluorine in crystal packing: insights from halogen substituted benzanilides

“…12 Furthermore, the presence of symmetry in the molecule has been shown to influence disorder in the fluorine position, for example, in 2-fluorobiphenyl, trans-4-fluoroazoxy-benzene and trans-4-fluoro-NNO-azoxybenzene. 13,14 The molecular assemblies in these structures have been shown to be stabilized by C-H/F hydrogen bonds. The question remains whether the intermolecular interactions are observed as a consequence of geometry alone.…”

“…In fact, the C-F bond length associated with the major occupancy fluorine is almost close to the standard C-F bond length (1.345 A), while the minor occupancy fluorine has a bond length lying between normal values of C-H and C-F bond. 14 Several of the possible combinations of fluorine substitution both on the aniline side and on the benzoyl side show disorder in fluorine positions. This article is mainly devoted to the discussion related to positional disorder in fluorine in halogen substituted benzanilides.…”

The non-planarity of the benzene molecule in the X-ray structure of the chelated bismuth(iii) heteroboroxine complex is not supported by quantum mechanical calculations

“…Although there is a plethora of procedures for crystal structure prediction and calculation based on ab initio methods or cooperation of X-ray, NMR and theoretical methods is reported 15 but to the best of our knowledge only one paper deals with a post-treatment of disordered small molecules. 16 An interesting observation was made when the positions of the carbon atoms obtained by theoretical calculations (a scan Fig. 4 ESP of the isolated chelated bismuth(III) heteroboroxine complex.…”