Preparation, structural and thermal studies of boroxine adducts having aryl boronic acids and pyrazoles

Four new boroxine adducts ((B3O3(Ph)3PzH) (1), (B3O3(Ph)3(PztBu,iPrH)2) (2), (B3O3(PhF2)3PzH). PzH (3) and (B3O3(PhF2)3(PztBu,iPrH)2) (4)) using phenylboronic acid, 3,5-difluorophenylboronic acid, 1H-pyrazole (PzH) and 3-tert-butyl-5-isopropyl pyrazole (PztBu,iPrH) were prepared and characterized by elemental analysis, IR, 1H-NMR and X-ray diffraction. The crystallographic study reveals that PzH and PztBu,iPrH are bonded to boroxine molecule through B-N dative bond. It also demonstrates the different type of hydrogen bond interactions between adjacent molecules. The thermal stability of these adducts was investigated by TGA. Key words: Boroxine, crystal structures, hydrogen bonding, thermal study.