Choice of hydrogen bonds or halogen bonds by 2-halogenated 5-morpholinomethylphenyl triazolo[1,5-]pyridine

The crystal structures of halogenated 1,2,4-triazolo[1,5- a ]pyridine derivatives disclose intriguing structural chemistry features dictated by the formation of either hydrogen bonds (HBs) or halogen bonds (XBs). 2-Chloride and bromide derivatives ( 1 and 2 ) favor HBs, promoting the formation of bent-shaped conformers. The 2-iodide compound ( 3 ) favors XBs, leading to different shaped conformers split into polymorphic forms. The XB-mediated crystals ( 3I and 3II ) are more thermodynamically stable than the HB-mediated crystals of 1 and 2 . The crystal structures of halogenated 1,2,4-triazolo[1,5- a ]pyridine derivatives disclose intriguing structural chemistry features dictated by the formation of either hydrogen bonds (HBs) or halogen bonds (XBs).