A Novel Conformation for a Coordinated Macrocycle: The Crystal Structure of [Ni(12-aneN₄)(OH₂)₂](CIO₄)₂·H₂O; (12-aneN₄= 1,4,7,10-Tetraazacyclododecane)

Abstract

Abstract The complex [Ni(12-aneN4)(OH2)2](ClO4)2·H2O (12-aneN4 = 1,4,7,10-tetraazacyclododecane) has been prepared and its structure determined. The complex crystallizes in the orthorhombic space group P212121 With a= 11.173(5), b = 11.976(5) and c = 13.969(4) Å. The volume of the unit cell is 1869(1) Å3. The total reflections collected for 2.0 ≤ 20 ≤ 50.0° were 1916 with 1895 being unique and 1659 used in the structure determination. Final values of R = 0.053 and R w = 0.057 were obtained. Our results indicate that this six coordinate Ni(II) species has a cis or folded geometry and that the coordinated tetraazamacrocyclic ligand exhibits a conformation that is unprecedented in the literature. In this new conformation three of the hydrogens coordinated to the nitrogens point towards the metal centre while only one hydrogen coordinated to a nitrogen points away from the metal centre.