Charge density of (-)-strychnine from 100 to 15 K, a comparison of four data sets

Strychnine has an interesting oligocyclic structure of seven condensed rings. It is easy to crystallize and gives crystals of excellent quality which diffract nicely to high regions in reciprocal space. It was thus chosen for a comparative charge-density study based on four high-resolution data sets (sin θ/λ ≥ 1.15 Å^-1) that were measured with different experimental setups in the temperature range 100-15 K. In addition, a theoretical charge density was derived from a B3LYP/6-311++G(3df,3pd) calculation. The agreement expressed in bond topological parameters among the four experimental charge densities is better than between experiment and theory.