The crystal and molecular structure of an isomer of Bromo [1,9-bis(2-pyridyl) 2,5,8-triazononane] cobalt(III), perchlorate, [Co( picdien)Br](ClO 42and that of an isomer of nitro[1,9-bis(2-pyridyl)2,5,8-triazanonane]cobalt(III), perchlorate, [Co picdien)(No 2)](ClO 4) 2

Abstract

The structure of an isomer of bromo [1,9-bis(2-pyridyl)2,5,8-triazanonane] cobalt(III), perchlorate, [Co(picdien)Br](ClO 4) 2, (I) and that of an isomer of nitro [1,9-bis(2-pyridyl)2,5,8-triazanonane]cobalt(III), perchlorate, [Co(picdien)(NO 2)](ClO 4) 2, (II), was determined by counter data. Crystal data are as follows: (I), a = 21.242(9), b = 21.732(9), 10.015(5) Å, orthorhombic, P b c a, Z = 8; (II), a = 10.062(5), b = 28.553(9), c = 7.894(4) Å, β = 97.9(1)°, monoclinic, I c, Z = 4. Full matrix least-squares refinement converged at R = 0.064, (I), and R = 0.068, (II). The coordination geometry of both complex cations is near regular octahedral, with the pentadentate picdein ligand present in the α, β configuration. The absolute configuration of (I) can be designed as Δ-α, β-R (or Λ-α, β-S) whereas that of (II) is Δ-α, β-S (or Λ-α, β-R). The ClO 4 anions assume a distorted tetrahedral configuration.