Crystal structure of the dihydroperchlorate of 1,4,8,11-tetra-azacyclotetradecane (cyclam)

Abstract

Three-dimensional crystal structure analysis by Patterson and Fourier methods has shown that the title compound consists of centrosymmetrical cations, two of the nitrogen atoms being protonated, and perchlorate ions. There is one formula unit [C₁₀H₂₆N₄][ClO₄]₂ in a triclinic unit cell of dimensions a= 8·081 (3), b= 8·657(3), c= 8·219(2)Å, α= 119·23(2), β= 95·05(3), γ= 111·37(2)°, space group P. Refinement by least-squares gave R 0·049 on 1009 diffractometer observations. In the perchlorate ion mean Cl–O is l·405(3)Å, uncorrected for libration. The cationic ring contains two centrosymmetrically related protonated nitrogen atoms (N–C 1·504 and 1·490, N–H 0·94 and 0·99 Å), and two secondary amine nitrogen atoms (N–C 1·464 and 1·470, N–H 0·91 Å). An approximately tetrahedral arrangement about the latter type is completed by a hydrogen atom from the former type which may be forming a weak hydrogen bond. Evidence for N–H ⋯ O hydrogen bonding is equivocal.