Co-operative halogen bonds and nonconventional sp-C—H...O hydrogen bonds in 1:1 cocrystals formed between diethynylpyridines and N-halosuccinimides

Abstract

The rapid evaporation of 1:1 solutions of diethynylpyridines and N-halosuccinimides, that react together to form haloalkynes, led to the isolation of unreacted 1:1 cocrystals of the two components. The 1:1 cocrystal formed between 2,6-diethynylpyridine and N-iodosuccinimide (C4H4INO2·C9H5N) contains an N-iodosuccinimide–pyridine I...N halogen bond and two terminal alkyne–succinimide carbonyl C—H...O hydrogen bonds. The three-dimensional extended structure features interwoven double-stranded supramolecular polymers that are interconnected through halogen bonds. The cocrystal formed between 3,5-diethynylpyridine and N-iodosuccinimide (C4H4INO2·C9H5N) also features an I...N halogen bond and two C—H...O hydrogen bonds. However, the components form essentially planar double-stranded one-dimensional zigzag supramolecular polymers. The cocrystal formed between 3,5-diethynylpyridine and N-bromosuccinimide (C4H4BrNO2·C9H5N) is isomorphous to the cocrystal formed between 3,5-diethynylpyridine and N-iodosuccinimide, with a Br...N halogen bond instead of an I...N halogen bond.