Peter R. Ireland

Acidopentaminecobalt(III) complexes with polyamine ligands. III. The crystal structure of β-chloro(ethylenediamine)(dipropylenetriamine)cobalt(III) tetrachlorozincate(II)

Abstract The crystal structure of β-chloro(ethylenediamine) (dipropylenetriamine)cobalt(III) tetrachlorozincate(II), β-[Co(en)(dpt)Cl]ZnCl4, has been determined by three-dimensional X-ray diffraction techniques from 799 reflections collected at ambient temperature by multiple film methods. The stucture has been solved by the symbolic addition procedure and refined by full-matrix least-squares techniques to a conventional R factor of 8.0%. The salt cystallises in space group P21/c of the monoclinic system with 4 formula units in a cell of dimensions a = 7.875(3), b = 15.824(11), c = 14.748(8)A, β = 94.69(5)°. The observed and calculated densities are 1.65 and 1.63 g/cm3 respectively. The cobalt atom is surrounded by one chlorine and five nitrogen atoms in an approximately octahedral configuration. The three nitrogen atoms of the dipropylenetriamine ligand (NH2(CH2)3NH(CH2)3NH2) are in a plane with one nitrogen atom of the ethylenediamine while the second nitrogen atom is trans to the chlorine atom. The orientation about the coordinated secondary amine nitrogen of the dipropylenetriamine is such that the NH proton is remote from the chlorine atom. The tetrachlorozincate(II) anion has a slightly distorted tetrahedral configuration, with an average ZnCl bond distance of 2.26(2) A.

Acidopentaminecobalt(III) complexes with polyamine ligands. IV. The crystal structure of α-chloro(ethylenediamine)(dipropylenetriamine)cobalt(III) iodide monohydrate and strain energy minimisation calculations for the α- and β-isomeric cations

Abstract The crystal structure of α-chloro(ethylenediamine) (dipropylenetriamine)cobalt(III) iodide monohydrate α-[Co(en)(dpt)Cl]I2. H2O has been determined by three dimensional X-ray diffraction techniques using 468 reflections collected at ambient temperature by multiple film methods. Full-matrix least-squares refinement led to a conventional R factor of 0.066. The salt crystallises in space group Pna21 of the orthorhombic system with 4 formula units in a cell of dimensions a=14.49, b=9.123, c=13.27 A. The observed and calculated densities are 2.09 and 2.11 g/cm3 respectively. The cobalt atom is surrounded by one chlorine and five nitrogen atoms in an approximately octahedral configuration. The three nitrogen atoms of the dipropylenetriamine ligand (NH2(CH2)3)NH(CH2)3NH2) are in a plane with one nitrogen atom of the ethylenediamine while the second nitrogen atom is trans to the chlorine atom. The orientation about the co-ordinated secondary amine nitrogen of the dipropylenetriamine, is such that the NH proton is adjacent to the chlorine atom. This is in contrast with the β-isomer, where the NH proton is remote from the chlorine atom. In both isomers, the fused six-membered ring systems adopt a ‘chair-boat’ conformation. Strain energy minimisation calculations have been performed on the α and the β-Co(en)(dpt)(Cl2+ isomers for ‘chair-chair’, ‘chair-boat’, and ‘chair-boat’ (inverted (λ) en ring) conformations of the dpt ligand. The energy difference between the most stable conformers (chair-boat, δ en as determined by crystal structure analysis) is small, with the α-isomer being 0.4 kcal/mole more stable.

X-Ray crystallographic determination of the infinite, helical, polymeric structure formed from acetylacetonato(trichloroacetato)copper(II) chemical units

The infinite, left-handed, helical structure of catena-µ-trichloroacetato-acetylacetonatocopper(II) has been determined by X-ray methods: each copper atom is surrounded by six oxygen atoms; two from a bidentate acetylacetonato-ligand, two from separate trichloroacetato-ligands which bridge to neighbouring copper atoms in the spiral, and two which are atoms of ligands bidentate to these neighbouring copper atoms.

Crystal structure of a cobalt(III) macrocyclic Schiff-base complex

The crystal structure of the Schiff-base complex dicyano-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclo-tetradeca-4,14-dienecobalt(III) perchlorate, [Co(C16N4H32)(CN)2]ClO4, has been determined from three-dimensional X-ray data collected photographically at room temperature. The crystals are orthorhombic, space group Pbca, with Z= 8 in a unit cell of dimensions a= 12·20(2), b= 21·28(5), and c= 18·45(3)A. The structure has been refined by least-squares techniques to R 9·9%. The stereochemical arrangement about the central cobalt atom is approximately octahedral, with cyanide groups above and below the macrocycle. The four nitrogen atoms of the quadridentate ligand are displaced significantly out of a least-squares plane through them, with an approximate mirror plane (not required crystallographically) perpendicular to the macrocycle through the centre of the cation. Oxygen atoms in the perchlorate anion show considerable anisotropic thermal motion.