Abstract: MATH/CHEM/COMP 2002, Dubrovnik, June 24-29, 2002

Solid State Dimerization of Nitroso Compounds

Selectivity and Reaction Mechanism

Hrvoj Vancik, Vesna simunic-Meznaric, Ernest Mestrovic, Srdjan Milovac, and Masa Raic

Department of Chemistry, Faculty of Science and Mathematics, University of Zagreb, Strossmayerov trg 14, 10000 Zagreb, Croatia

Monomer-dimer equilibrium of nitroso compounds was investigated in the solid state under cryogenic photochemical conditions. It was found that nitroso dimers can be UV-photolytically converted to nitroso monomers at 12 K, and reverted to dimers by visible light irradiation or warming above 170 K. Such a photo-thermal “chemical switch” by which it is possible to break the chemical bond between two nitrogen atoms, and bind them again, could potentially be used in supramolecular self-assembly systems. Since the reaction is controlled by topochemical factors, the reaction mechanism should be investigated by “orientational” methods. Consequently, the phenomenon was studied spectroscopically by linear dichroism technique in a series of cyclic and polycyclic nitroso compounds.

Selectivity in formation of mixed dimers, which could be important for supramolecular chemistry of nitroso compounds, is studied in solid state and in solution by NMR, UV-VIS, FT-IR and X-ray diffraction methods.