CRYSTAL STRUCTURES OF HIGH- AND LOW-SPIN NICKEL(II) COMPLEXES CONTAINING MACROCYCLIC LIGAND TETRABENZO[B,F,J,N][1,5,9,13]TETRAAZACYCLOHEXADECINE

The crystal structures of Ni(TAAB)I2·H2O and Ni(TAAB)(BF4)2, where TAAB is the tetradentate macrocyclic ligand tetrabenzo[b,f,j,n] [1,5,9,13]tetraazacyclohexadecine, have been determined from three-dimensional single-crystal X-ray diffraction data collected by automatic counter methods. The structure of Ni(TAAB)I2·H2O has been refined by leastsquares techniques to a conventional R factor of 10.9% for 1368 reflections, and the structure of Ni(TAAB)(BF4)2 has been refined to an R factor of 14.1% for 1709 observed reflections. The compound Ni(TAAB)I2·H2O crystallizes in the monoclinic space group C2/c with cell dimensions a = 13.48 ± 0.03 Å, b = 16.03 ± 0.03 Å, c = 13.51 ± 0.03 Å, and β = 90.9 ± 0.1°. The calculated density for Z=4 is 1.69 g/cm3 as compared to an experimental density of 1.76 g/cm3. The compound Ni(TAAB)(BF4)2 crystallizes in the monoclinic space group P21/c with cell dimensions of a = 11.55 ± 0.02 Å, b = 13.76 ± 0.03 Å, c = 19.59 ± 0.04 Å, and β = 123.0 ± 0.01°. The calculated density for Z = 4 is 1.64 g/cm3 as compared to a measured density of 1.61 ± 0.05 g/cm3. The structure consists of discrete molecules with the macrocyclic ligands having approximately S4(4) symmetry. In the compound Ni(TAAB)I2·H2O, the nickel(II) ion has tetragonal coordination with inplane Ni-N distances of 2.09 ± 0.03 Å corresponding to nickel(II) in the high-spin form. The apical positions are occupied by an iodide ion (the Ni-I distance is 2.903 ± 0.007 Å) and by a water molecule (the Ni-O distance is 2.20 ± 0.03 Å). The nickel(II) ion has planar coordination in the compound Ni(TAAB)(BF4)2 with average Ni-N distances of 1.90 + 0.02 Å corresponding to nickel(II) in the low-spin form. In both cases, disorder due to alternative orientations of packing of the molecules in the crystal has limited the accuracy of the macrocyclic ligand bond parameters. © 1969, American Chemical Society. All rights reserved.