A NOVEL CONFORMATION FOR A COORDINATED MACROCYCLE - THE CRYSTAL-STRUCTURE OF [NI(1,4,7,10-TETRAAZACYCLODODECANE)(OH2)2](CLO4)2.H2O

The complex [Ni(12-aneN4)(0H2)2](C104)2*H20 (12-aneN4 = 1, 4, 7, 10-tetraazacyclododecane) has been prepared and its structure determined. The complex crystallizes in the orthorhombic space group i521212lwith a = 11.173(5), 6= 11.976(5) and c = 13.969(4) A. The volume of the unit cell is 1869(1) A3. 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 Rw= 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 lig and 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. © 1990, Taylor & Francis Group, LLC. All rights reserved.