THE SYNTHESIS AND CRYSTAL-STRUCTURE OF [NIL(NCS)(2)] (L = -HYDROXYETHYL-1,3,5,8,12-PENTAAZACYCLOTETRADECANE)

The reaction of H2CO and H2NCH2CH2OH with the nickel(II) complex of 1, 9-diamino-3,7-diazanonane (2,3,2-tet) in the presence of Et3N gives th e nickel(II) complex of the macrocycle 3-hydroxyethyl-1,3,5,8,12-penta azacyclotetradecane (L), which can be readily isolated as the perchlor ate salt, The reaction of KCNS with the perchlorate salt in aqueous so lution gives [NiL(NCS)(2)] and the crystal structure of this complex h as been determined. The complex is octahedral and ti ans with the two N-bonded thiocyanates in the axial sites with Ni-NCS bond lengths of 2 .106 and 2.145 Angstrom. The equatorial sites are occupied by N-2, N-5 , N-8 and N-12 with Ni-N bond distances of 2.053 to 2.076 Angstrom, wh ich are typical for octahedral nickel(II) complexes, The ligand has a trans III configuration of the sec-NH centres, leading to chair six-me mbered rings and gauche five-membered rings. The hydroxyethyl group on N-3 is axial. There is no evidence for hydrogen-bonding interactions involving the hydroxyethyl group in the crystal lattice.