Study of the Linkage Isomerization [Co(NH3)5NO2]Br2⟺ [Co(NH3)5ONO] Br2 in the Solid State by X-ray Powder Diffraction

The solid-state linkage isomerization [Co(NH3)5NO2]Br2⟺ [Co(NH3)5ONO] Br2 was studied, at room temperature, using the X-ray powder diffraction technique. The structure of the photochemically synthesized [Co(NH3)5-ONO]Br2 was solved in the orthorhombic space group Cmcm, with a = 10.8011(7) Å, b = 8.9692(6) Å, c = 10.6090(6) Å, and Z = 4, and refined by the Rietveld method, down to Rprofile= 0.119, for 4000 data points collected in the 10-90° (2θ) range. The changes in the lattice parameters and the structural evolution in the course of the ONO ⟹ NO2 linkage isomerization showed the intramolecular nature of the isomerization, with the powders remaining a monophase system at any time. © 1994, American Chemical Society. All rights reserved.