Naslov
Dimerisation and oxygen loss upon crystallisation of nitroso compounds

Autori
Višnjevac, Aleksandar ; Milovac, Srđan ; Šimunić- Mežnarić, Vesna ; Kojić-Prodić, Biserka ; Vančik, Hrvoj

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
11th Slovenian-Croatian crystallographic meeting - book of abstracts / Leban, Ivan ; Popović, Stanko - Ljubljana : Univerza v Ljubljani, 2002, 28-28

Skup
11th Slovenian-Croatian crystallographic meeting

Mjesto i datum
Bohinj, Slovenija, 27.06.2002. - 30.06.2002

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
dimerisation ; oxygen loss ; crystallisation ; nitroso compounds

Sažetak
Most of the organic nitroso compounds exist as colourless dimers in solid state, and/or as green or blue monomers in solution.1 Crystallisation process implies simultaneous dimerisation. Nevertheless, these compounds reveal reversible dissociation/association under photochemical conditions in solid state, and as such they represent a simple and effective photochromic system.2 Dimers of p-bromonitrosobenzene (1), p- iodonitrosobenzene (2), p-nitronitrosobenzene (3) and p-methylnitrosobenzene (4) were studied by X- ray crystallography. Unprecedented lack of oxygen atoms in what was expected to be an azodioxy moiety was encountered in all of the presented structures. Furthermore, the structures 3 and 4 (Figs. 1 and 2) reveal disorder of the azo group over two positions, with s.o. 0.70 and 0.30. Two independent positions of nitrogen atoms appeared clearly in a Fourier difference map, whereas it was impossible to resolve discrete positions of disordered C-atoms of the benzene rings which, as a consequence, reveal slightly increased values of displacement parameters. For structure 3, the non- centrosymmetric space group P21 is reported due to a large number of reflections disobeying extinction rules for P21/c (in which, however, refinement converges as well). Molecules of 1 and 2 reveal crystallographic inversion centre at the midpoint of the N-N bond, having half a molecule in an asymmetric unit of the space groups P21/c and Pbcn, respectively. The molecule of 4 is of C1 symmetry, occupying general position.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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