An Investigation into the Bonding of Copper(I) Macrocycles to Fifth Ligands

The properties and reactivities of an unusual copper(I) macrocyclic complex have been investigated. The complex, Cu(LBF2) (l,l-difluoro- 4,S,ll,12-tetramethyl-l-bora-3,6,10,13-tetraaza-2,14-dioxo-cyclo-tetradeca-3,S,10,12-tetraenatocopper(I)), reacts with carbon monoxide to form an isolable complex, Cu(LBF2)CO. The crystal structure of Cu(LBF2)CO, which was previously determined, shows a square-pyramidal geometry around copper(I) with an apical carbon monoxide and four basal nitrogens. The crystal and molecular structure of the four-coordinate complex, Cu(LBF2), was determined. The copper binds to the four nitrogens of the macrocycle in a distorted square-planar array. The nitrogens are twisted toward a tetrahedron with resulting dihedral angles of 23 and 27° between the two sets of planes defined by copper and two adjacent nitrogens. The amount of the tetrahedral distortion is limited by the macrocycle's steric limitations.