Cocrystallization of chiral cobalt complexes via formation of quasiracemates
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Ullrich Englert
Starting from the enantiomerically pure or racemic nucleophile 1-phenylethylamine (L) chiral cobalt complexes with the general formula [Co(Hdmg)2XL] (Hdmg = dimethylglyoximate, X = CN, NO2) were obtained as homochiral or heterochiral crystalline solids, respectively. The crystal structures of the resulting cyano and nitro complexes were determined by single crystal X-ray diffraction. The homochiral solids crystallize in space group P21 with two molecules per asymmetric unit, the racemates in P21/c with only one independent molecule. From a solution containing equimolar amounts of enantiomerically pure S-L cyano and R-L nitro complexes a stable and well-ordered binary solid could be crystallized and structurally characterized. The molecular constituents of opposite chirality are arranged in pairs in the vicinity of pseudo inversion centers forming a quasi-racemate in space group P21. The driving force for the formation of this cocrystal is discussed in terms of intermolecular geometry and energy: The crystal structures of all five complexes are similar with respect to lattice parameters and intermolecular arrangement, but comparisons based on space filling and lattice energy confirm higher packing efficiency for the racemates and the quasi-racemate than for the enantiopure compounds.
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Articles in the same Issue
- Cocrystallization of chiral cobalt complexes via formation of quasiracemates
- An X-ray profile analysis on the growth imperfections and internal strains in vapour-deposited lead films
- Solving crystal structures without Fourier mapping. II. Non-centrosymmetric case
- On the question of commensurability – The Nowotny chimney-ladder structures revisited
- Analysis of occupational and displacive disorder using the atomic pair distribution function: a systematic investigation
- The nature of the incommensurate structure in åkermanite, Ca2MgSi2O7, and the character of its transformation from the normal structure
- Thermal annealing of metamict titanite: A synchrotron radiation and optical birefringence study
- Thermal motion of the univalent metal ions in KCr5S8-type chalcogenides, ternary chromium selenides MxCr5Se8 (M = Rb, Cs)
- An electron diffraction study of Cu ordering in Cu2.33-xV4O11
- Variable temperature study of the crystal structure of paracetamol (p-hydroxyacetanilide), by single crystal neutron diffraction
- A comparison of the molecular and crystal structures of the dimethylacetamide complexes from zinc chloride, bromide, and iodide
