UNUSUAL STRUCTURAL AND REACTIVITY TYPES FOR COPPER - STRUCTURE OF A MACROCYCLIC LIGAND COMPLEX APPARENTLY CONTAINING COPPER(I) IN A DISTORTED SQUARE-PLANAR COORDINATION GEOMETRY

The diamagnetic macrocyclic ligand complex [l,l-difluoro-4,5,11,12-tetramethyl-l-bora-3,6,10,13-tetraaza-2,14-dioxa-cyclotetradeca-3,5,10,12-tetraenato]copper(I), Cu(LBF2), reacts with monodentate ligands including CO to give five-coordinate Cu(I) adducts, e.g., Cu(LBF2)CO, 1. The crystal and molecular structure of the four-coordinate complex Cu(LBF2), 2, was determined in order to help elucidate the nature of the adduct formation reaction. Complex 2 crystallized in the space group P21/n (No. 14) with a=11.800 (2) υ, b=9.005 (1) υ, c=13.704 (1) υ, β=96.40 (1)°, and Z=4. An R(F) of 0.054 was obtained using 2882 reflections to 26=140°. The complex contains isolated mononuclear molecules with no significant intermolecular interactions. Each copper atom is bound by the four nitrogens of the macrocyclic ligand in a near-square-planar array, resulting in a highly unusual structural environment for Cu(I). The four nitrogens are, however, tetrahedrally distorted from planarity, with dihedral angles of 23 and 27° for the two sets of planes defined by copper and two adjacent nitrogen atoms. Copper-nitrogen bond lengths average to 1.939 (3) υ. The infrared spectrum of 2 exhibits no bands in the 1500-1700-cm1 region expected for the ligand α-diimine moiety but does not show two bands at 1320 and 1470 cm-1 which might be associated with a-diimine stretching modes. The infrared spectra of 1 and 2, as well as crystallographic, electrochemical, and magnetic data, are used to discuss a reasonable description for the oxidation state of copper in both 1 and 2. © 1978, American Chemical Society. All rights reserved.