Probabilistic model-based methodology for the conformational study of cyclic systems: application to copper complexes...

A methodology for the conformational study of cyclic systems through the statistical analysis of torsion angles is presented. It relies on a combination of different methods based on a probabilistic model which takes into account the topological symmetry of the structures. This methodology is applied to copper complexes double-bridged by phosphate and related ligands. Structures from the Cambridge Structural Database (CSD) are analyzed and the chair, boat-chair and boat conformations are identified as the most frequent conformations. The output of the methodology also provides information about distortions from the ideal conformations, the most frequent being: chair <--> twist-chair, chair <--> twist-boat-chair and boat <--> twist-boat. Molecular mechanics calculations identify these distortions as energetically accessible pathways.