Crystal and molecular structure of racemic cis-α-[CoL(NO2)2][BF4] and cis-α-[CoL(NO2)2][BF2O](L = 3,6-dithiaoctane-1,8-diamine), a compound containing an anion newly isolated in crystalline form

Abstract

Two compounds crystallized as racemates from the same crystallization batch, derived from a water solution of [CoL(NO₂)₂][BF₄]1, (L = 3,6-dithiaoctane-1,8-diamine) which had stood for several weeks at 21 °C. The crystals have totally different morphology and were manually separated: 1, orthorhombic, space group Pca2₁, Z= 8, a= 12.811(3), b= 12.213(6), c= 18.906(8)Å, R= 0.0433, R′= 0.0481 for 1498 unique reflections; cis-α-[CoL(NO₂)₂][BF₂O]2, monoclinic, space group P2₁/n, Z= 4, a= 8.054(4), b= 13.833(4), c= 12.564(8)Å, β= 105.26(4)°, R= 0.0491, R′= 0.0578 for 2022 unique reflections. In both compounds the organic ligand is quadridentate with two trans-axial nitrogen and two cis sulfur donor atoms located trans to the two basal NO₂ ligands. Likewise, in both, the counter anion is hydrogen bonded to the terminal NH₂ hydrogens. Complex 2 contains the BF₂O^– anion which had, heretofore, not been isolated in crystalline form. In both cases the cations are in the cis-α configuration, having Λ(δλλ) and Δ(λλδ) pairs as the asymmetric units of 1 and 2.