STRUCTURAL VARIATIONS IN MACROCYCLIC COPPER(II) COMPLEXES - CRYSTAL AND MOLECULAR-STRUCTURE OF IODO[DIFLUORO[3,3'-(TRIMETHYLENEDINITRILO)BIS(2-BUTANONE OXIMATO)]BORATO]COPPER(II), [CU(CYCLOPS)I]

The crystal and molecular structure of [Cu(cyclops)I] (1, cyclops = difluoro[3, 3‘-(trimethylenedinitrilo)bis(2-butanone oximato)] borate) has been determined from three-dimensional single-crystal X-ray diffraction data, collected by counter techniques. The dark green crystals of 1 were monoclinic, space group P21/c (No. 14), with four formula units in the unit cell (a = 10.036 (3) Å, b = 7.399 (3) Å, c = 24.982 (8) Å, β = 106.67 (1)°). The structure of 1 was refined to R = 0.046 (Rw, = 0.047) for 1488 independent reflections with F2 > 3σ(F2). The discrete, monomeric complex ions exhibited square-pyramidal coordination geometry about the central copper(II) ion, with iodide occupying the apical position and the four basal coordination sites being occupied by the nitrogen atoms of the quadridentate macrocyclic cyclops ligand. The flexible macrocyclic ligand allows a large displacement (0.38 A) of the copper(II) ion out of the basal plane of four nitrogen atoms in the direction of the apical iodo ligand; while simultaneously maintaining strong copper(II)-nitrogen bonding (Cu-N(av) = 1.956 (7) Å). A very short, strong bond is observed between the metal atom and the apical iodo ligand (Cu-I = 2.742 (2) A), which underscores the ability of the cyclops macrocycle to allow very strong bonds to be formed to ligands in the apical position of a square-pyramidal coordination environment about copper(II). © 1979, American Chemical Society. All rights reserved.