Received 14 June 2013
Practical chemistry courses at universities very frequently propose the synthesis and characterization of [Co(CO3)(NH3)4]NO3, but this goal is never achieved since students only obtain the hemihydrated form. The anhydrous form can be prepared, however, and its structure is presented here. Similar to the hemihydrate form, the anhydrous phase contains the CoIII ion in an octahedral O2N4 coordination by a chelating carbonate group and four ammine ligands. The structure reveals an intricate array of N-HO hydrogen bonds involving both the chelating and the non-chelating O atoms of the carbonate ligand as hydrogen-bond acceptors of the amine H atoms, which are also involved in hydrogen-bonding interactions with the nitrate O atoms. The structure of the anhydrous form is close to that of the hemihydrate phase, suggesting a probable topotactic reaction with relatively small rotations and translations of the [Co(CO3)(NH3)4]+ and NO3- groups during the dehydration process, which produces an unusual volume increase of 4.3%.
For the crystal structure of the hemihydrate, see: Bernal & Cetrullo (1990); Junk & Steed (1999); Christensen & Hazell (1999). For the synthesis of the hemihydrate, see: Schlessinger (1960). For powder diffraction indexing figures of merit, see: de Wolff (1968); Smith & Snyder (1979). For profile refinement by the Le Bail method, see: Le Bail (2005). For preferred orientation correction, see: Dollase (1986).
Data collection: DIFFRAC-AT (Siemens & Socabim, 1993); cell refinement: McMaille (Le Bail, 2004); data reduction: DIFFRAC-AT; program(s) used to solve structure: ESPOIR (Le Bail, 2001); program(s) used to refine structure: FULLPROF (Rodriguez-Carvajal, 1993); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: VN2075 ).
The author thanks J. H. Zhu and H. X. Wu for the synthesis of the hemihydrate phase and A. M. Mercier for the TGA and DSC experiments.
Bernal, I. & Cetrullo, J. (1990). Struct. Chem. 1, 227-234.
Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.
Christensen, A. N. & Hazell, R. G. (1999). Acta Chem. Scand. 53, 399-402.
Dollase, W. A. (1986). J. Appl. Cryst. 19, 267-272.
Junk, P. C. & Steed, J. W. (1999). Polyhedron, 18, 3593-3597.
Le Bail, A. (2001). Mater. Sci. Forum, 378, 65-70.
Le Bail, A. (2004). Powder Diffr. 19, 249-254.
Le Bail, A. (2005). Powder Diffr. 20, 316-326.
Rodriguez-Carvajal, J. (1993). Physica B, 192, 55-69.
Schlessinger, G. (1960). Inorg. Synth. 6, 173-175.
Siemens & Socabim (1993). DIFFRAC-AT. Siemens Analytical X-ray Instruments, Inc., Madison, Wisconsin, USA, and Socabim SA, Paris, France.
Smith, G. S. & Snyder, R. L. (1979). J. Appl. Cryst. 12, 60-65.
Spek, A. L. (2009). Acta Cryst. D65, 148-155.
Wolff, P. M. de (1968). J. Appl. Cryst. 1, 108-113.