I. E. Maxwell

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.

Novel cation sited in a dehydrated divalent copper-exchanged zeolite

Single-crystal X-ray analysis has shown that in dehydrated divalent copper-exchanged faujasite the so-called site III-type cations are located at the pore entrances to the supercage and are effectively bonded to only one framework oxygen, thus being present in a highly unsaturated co-ordination geometry.