| الملخص: | In order to study the effect of halogen bond on tautomerism in β-diketones in the solid-state, we have prepared a series of cocrystals derived from an asymmetric β-diketone, benzoyl-4-pyridoylmethane (<b>b4pm</b>), as halogen bond acceptor and perfluorinated iodobenzenes: iodopentaflourobenzene (<b>ipfb</b>), 1,2-, 1,3- and 1,4-diiodotetraflorobenzene (<b>12tfib</b>, <b>13tfib</b> and <b>14tfib</b>) and 1,3,5-triiodo-2,4,6-trifluorobenzene (<b>135titfb</b>). All five cocrystals are assembled by I···N halogen bonds involving pyridyl nitrogen and iodoperfluorobenzene iodine resulting in 1:1 (four compounds) or 1:2 (one compound) cocrystal stoichiometry. Tautomer of <b>b4pm</b> in which hydrogen atom is adjacent to the pyridyl fragment was found to be more stable <i>in vacuo</i> than tautomer with a benzoyl hydroxyl group. This tautomer is also found to be dominant in the majority of crystal structures, somewhat more abundantly in crystal structures of cocrystals in which additional I···O halogen bond with the benzoyl oxygen has been established. Attempts have also been made to prepare an equivalent series of cocrystals using a closely related asymmetric β-diketone, benzoyl-3-pyridoylmethane (<b>b3pm</b>); however, all attempts were unsuccessful, which is attributed to more effective crystal packing of <b>b3pm</b> isomer compared to <b>b4pm</b>, which reduced the probability of cocrystal formation.
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