Extremely Facile Template Synthesis of Gold(III) Complexes of a Saturated Azamacrocycle and Crystal Structure of a Six-Coordinate Gold(III) Complex

Two gold(III) complexes of the hexaazamacrocyclic ligand 1,8-bis(hydroxyethyl)-1,3,6,8,10,13-hexaazacyclotetradecane ( L ), four-coordinate [Au( L )](ClO 4 ) 3 · 1 / 2 H 2 O and six-coordinate [Au( L )Cl 2 ]AuCl 4, were synthesized in high yield from the template condensation of ethylenediamine, formaldehyde, and ethanolamine in the presence of gold(III) ion. The gold(III) template cyclization is extremely fast compared with the corresponding nickel(II) template reaction. Both gold(III) complexes are diamagnetic. [Au( L )Cl 2 ]AuCl 4 (Au 2 C 12 H 30 N 6 O 2 Cl 6 ) crystallizes in the monoclinic space group P 2 1 / c with a = 6.987(2) Å, b = 14.945(1) Å, c = 11.151(3) Å, β = 98.83(1)°, and Z = 2. The structure was solved by Patterson and the direct methods and refined to R values of R = 0.0868 and R w ( F 2 ) = 0.1324 for 2025 observed reflections measured with Mo Kα radiation on an Enraf Nonius CAD-4 diffractometer. The gold(III) ion of the macrocyclic cation displays a tetragonally distorted octahedral geometry, with four nitrogens in the plane and two chlorides on axial sites. The bond distances of Au−N and Au−Cl average 2.049(8) and 3.097(4) Å, respectively. The hydrogen atoms of secondary amines form hydrogen bonds with hydroxyl oxygen and the coordinated chloride of neighboring macrocyclic complexes.