Effects of larger chelate rings on the geometry and properties of copper(II) complexes. Crystal and molecular structure and spectral properties of aquo(1,1-difluoro-4,5,12,13-tetramethyl-1-bora-3,6,11,14-tetraaza-2,15-dioxacyclopentadeca-3,5,11,13-tetraenato)copper(II) perchlorate Academic Article uri icon

abstract

  • The crystal and molecular structure of aquo(1,1 -difluoro-4,5,12,13-tetramethyl-1 -bora-3,6,11,14-tetraaza-2,15-dioxacyclopentadeca-3,5,11,13-tetraenato)copper(II) perchlorate, C12H22BClCUF2N4O7, has been determined by single-crystal X-ray diffraction methods. The space group is P21/c with a = 9.663 (2) Å,b= 13.401 (2) Å,c= 15.012 (3) Å, and β = 95.11 (2)°. Refinement using 2214 unique reflections with I > 3σ (I) gave an unweighted R factor of 0.052 and a weighted R factor of 0.073. The structure is essentially square pyramidal with the aquo ligand at the apex. The nitrogen donors are alternately above and below the best basal plane for the square pyramid by about 0.1 Å, and the aquo ligand is distorted from the ideal apical position, probably due to interaction with an F atom of the BF, group within the six-membered ring. The Cu-aquo O distance is 2.250 (3) Å, and the average Cu-N distance is 1.972 (8) Å. The effects of the seven-membered chelate ring on the structure and on other properties of the complex are discussed. Visible spectral data are discussed for the complex cations (2-oximino-11-oximato-3,10-dimethyl-4,9-diazadodeca-3,9-diene)copper(II), C12H21CUN4O2+, and (1,1-difluoro-4,5,12,13-tetramethyl-1-bora-3,6,11,14-tetraaza-2,15-dioxacyclopentadeca-3,5,11,13-tetraenato)copper(II), C12H22BCUF2N4O2+, with various axial ligands. These complexes do not follow the usual spectrochemical series. Axial ligands which bind strongly to copper(II) pull it further from the basal nitrogen plane, reducing the crystal field splitting caused by these donors. The perturbed spectrochemical series observed for these complexes is different from that observed for the copper(II) complexes of an analogous 14-membered macrocycle. The differences are attributed to the geometrical distortions resulting from the presence of the seven-membered chelate ring in the 15-membered macrocycles. Spectra of the complex cation (2,3,10,11 -tetramethyl-1,4,9,12-tetraazacyclohexadeca-1,3,9,11-tetraene)copper(II), C16H28CuN42+, are indicative of tetrahedral distortion from square-planar geometry or of square-pryamidal geometry. Current macrocycle nomenclature is extended to cover compounds having heteroatoms which do not serve as donors. © 1981, American Chemical Society. All rights reserved.

author list (cited authors)

  • Martin, J., Timmons, J. H., Martell, A. E., Rudolf, P., & Clearfield, A.

citation count

  • 14

publication date

  • March 1981