Acidopentaminecobalt(III) complexes with polyamine ligands. VI. The crystal structures of the π(racemic)- and χ-chloro(ethylenediamine)(diethylenetriamine)cobalt(III) tetrachlorozincate(II) salts

Abstract

The crystal structures of the π(racemic)- and χ-chloro(ethylenediamine) (diethylenetriamine)cobalt(III) tetrachlorozincate(II) salts, π and χ-[Co(en)(dien)Cl]ZnCl 4, have been determined from three-dimensional X-ray data collected by counter methods at 23°. The crystals of the π isomer are monoclinic: space group C 2h 5-P2 1/n with four molecules in a cell of dimensions a = 13.745(3), b = 8.202(2), c = 15.117 (6) Å, β 98.56(1)°. Observed and calculated densities are 1.85 (±0.01) and 1.85 g. cm -3. Least-squares refinement of the structure has led to a final value of the conventional R-factor (on F) of 0.061 for the 2098 reflections having F 2⩾σ(F 2). The structure consists of an equimolar mixture of two enantiomorphic cations and discrete tetrachlorozincate(II) anions. The crystals of the χ isomer are monoclinic: space group C 5 4Cc, with four molecules in a unit cell of dimensions a = 9.676(1), b = 12.790(2), c = 13.888 (3) Å, β = 93.63(1)°. Observed and calculated densities are 1.83 (±0.010 and 1.83 g. cm -3. A final value of the conventional R-factor (on F) of 0.057 was obtained from the 1353 reflections having F 2⩾3σ(F 2). This structure consists of the complex cation and discrete tetrachlorozincate(II) anions. In both isomers, the complex cations contain the cobalt atom surrounded by one chlorine atom and five nitrogen atoms in an approximately octahedral configuration. For the π isomer, the three nitrogen atoms of the diethylenetriamine ligand are in a facial configuration and the chlorine atom occupies one of the two equivalent cis positions relative to the coordinated secondary amine group of the diethylenetriamine. The ethylenediamine ligand occupies the remaining two coordination positions. For the χ isomers, the three nitrogen atoms of the diethylenetriamine ligand are in a plane with one nitrogen atom of the ethylenediamine ligand, while the second ethylenediamine nitrogen atom is trans to the chlorine atom. The orientation about the secondary nitrogen group of the diethylenetriamine ligand is such that the NH proton is remote from the coordinated chlorine atom. In both salts, the tetrachlorozincate(II) anions have slightly distorted tetrahedral configurations.