Electron density, disorder and polymorphism: high-resolution diffraction studies of the highly polymorphic neuralgic drug carbamazepine.
Acta Crystallogr B Struct Sci Cryst Eng Mater
; 72(Pt 1): 39-50, 2016 Feb.
Article
in En
| MEDLINE
| ID: mdl-26830795
ABSTRACT
Analysis of neutron and high-resolution X-ray diffraction data on form (III) of carbamazepine at 100 K using the atoms in molecules (AIM) topological approach afforded excellent agreement between the experimental results and theoretical densities from the optimized gas-phase structure and from multipole modelling of static theoretical structure factors. The charge density analysis provides experimental confirmation of the partially localized π-bonding suggested by the conventional structural formula, but the evidence for any significant C-N π bonding is not strong. Hirshfeld atom refinement (HAR) gives H atom positional and anisotropic displacement parameters that agree very well with the neutron parameters. X-ray and neutron diffraction data on the dihydrate of carbemazepine strongly indicate a disordered orthorhombic crystal structure in the space group Cmca, rather than a monoclinic crystal structure in space group P2(1)/c. This disorder in the dihydrate structure has implications for both experimental and theoretical studies of polymorphism.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Carbamazepine
Type of study:
Prognostic_studies
Language:
En
Journal:
Acta Crystallogr B Struct Sci Cryst Eng Mater
Year:
2016
Document type:
Article
Affiliation country:
United kingdom