Buy article online - an online subscription or single-article purchase is required to access this article.
organic compounds
In the solid state, trans-2,6-diphenyl-4-(hydroxyimino)piperidinol, C17H18N2O2, (1), trans-2,6-di(1-methylpyrrol-2-yl)-4-(hydroxyimino)piperidinol, C15H20N4O2, (2) and trans-2,6-di(thien-2-yl)-4-(hydroxyimino)piperidinol, C13H14N2O2S2, (3) adopt conformations with an axial OH substituent on the ring N atom, in contrast to the preference for an equatorial conformation in solution. Molecules of all three structures are held together in chains by hydrogen bonding.