Crystal structure and halogen–hydrogen bonding of a Delépine reaction inter­mediate

The reaction of 1,5-di­bromo­pentane with urotropine results in crystals of the title mol­ecular salt, 5-bromo­urotropinium bromide [systematic name: 1-(5-bro­mo­pent­yl)-3,5,7-tri­aza-1-azoniatri­cyclo­[3.3.1.13,7]decane bromide], C11H22BrN4+·Br− (1), crystallizing in space group P21/n. The packing in compound 1 is directed mainly by H⋯H van der Waals inter­actions and C—H⋯Br hydrogen bonds, as revealed by Hirshfeld surface analysis. Comparison with literature examples of alkyl­urotropinium halides shows that the inter­actions in 1 are consistent with those in other bromides and simple chloride and iodide species