Cathleen M. Crudden and her team from Queen’s University, Canada, have added to the rare series of organometallic single-crystal-to-single-crystal transformations. These types of chemical transformations occur in the solid state without disruption of crystalline order.

They demonstrated that rhodium NHC complexes undergo back-to-back single-crystal-to-single-crystal transformations by selective nonreversible ligand exchange reactions. See rhodium complexes ligated by different NHC ligands on the picture.

Slow diffusion of O₂ converts a dinitrogen complex into a dioxygen complex, and CO subsequently replaces O₂. The possible applications for this process include crystal engineering and chemical sensing.

• Double Single-Crystal-to-Single-Crystal Transformation and Small-Molecule Activation in Rhodium NHC Complexes,
  Olena V. Zenkina, Eric C. Keske, Ruiyao Wang, Cathleen M. Crudden,
  Angew. Chem. 2011.
  DOI: 10.1002/ange.201103316
• Angew. Chem. Int. Ed. 2011.
  DOI: 10.1002/anie.201103316