The 7-aza-norbornane nucleus of epibatidine: 7-aza-bicyclo-[2.2.1]heptan-7-ium chloride

Crystal structure of (1S,4S)-2,5-diazo-niabi-cyclo[2.2.1]heptane dibromide

The cage of 2,5-di-aza-bicyclo-[2.2.1]heptane is frequently employed in synthetic chemistry as a rigid bicyclic counterpart of the piperazine ring. The 2,5-di-azabicyclo-[2.2.1]heptane scaffold is incorporated into a variety of compounds having pharmacological and catalytic applications. The unsubstituted parent ring of the system, 2,5-di-aza-bicyclo-[2.2.1]heptane itself, has not been structurally characterized. We herein report on the mol-ecular structure of the parent ring in (1S,4S)-2,5-diazo-niabi-cyclo-[2.2.1]heptane dibromide, C5H12N22+·2Br-. The asymmetric unit contains two crystallographically independent cages of 2,5-di-aza-bicyclo-[2.2.1]heptane. Each cage is protonated at the two nitro-gen sites. The overall charge balance is maintained by four crystallographically independent bromide ions. In the crystal, the components of the structure are linked via a complex three-dimensional network of N-H⋯Br hydrogen bonds.

Crystal structure of (1R,5S)-endo-(8-methyl-8-azoniabi-cyclo-[3.2.1]oct-3-yl)ammonium aqua-tri-chlorido-nitratocopper(II)

The structure of a salt of diprotonated endo-3-amino-tropane crystallized with a copper(II) anionic cluster is reported, viz. (C8H18N2)[CuCl3(NO3)(H2O)]. Neither ion in the salt has been structurally characterized previously. In the crystal, the ions pack together to form a three-dimensional structure held together by a network of inter-molecular N-H⋯O, O-H⋯Cl and N-H⋯Cl hydrogen-bonding inter-actions. Selective crystallization of the title compound can be considered as a simple method for the separation of the exo and endo isomers of 3-amino-tropane.