STRUCTURE OF THE MACROCYCLIC LIGAND TETRAKIS(2-HYDROXYETHYL)CYCLAM AT 123-K

1,4,8,11-Tetrakis(2-hydroxyethyl)-1,4,8,11-tetraazacyclotetradecane, C18H40N4O4, M(r) = 376.54, monoclinic, P2(1)/n, a = 9.945 (1), b = 9.562 (1), c = 11.116 (1) angstrom, beta = 100.03 (1)-degrees, V = 1040.9 (2) angstrom3, Z = 2, D(x) = 1.201 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 0.079 mm-1, F(000) = 416, T = 123 (2) K, R = 0.041 for 1513 unique reflections. The macrocyclic ligand crystallizes in the RSSR (trans IV) configuration on a crystallographic centre of symmetry, with the electron pairs on 1,8-related N atoms directed away from the centre of the ring. Thus it is not possible from this structure to determine accurately the dimensions of the metal ion binding cavity. Intramolecular hydrogen bonding brings together 1,4-related hydroxyl groups in an association which also involves the N atoms to which they are appended. There is no indication of significant intermolecular hydrogen bonding.