Conformations of malonate chelate rings: the crystal and molecular structure of sodium (+)546ethylenediaminebis(malonato)cobaltate(III) dihydrate
- 1 January 1976
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 3,p. 259-262
- https://doi.org/10.1039/dt9760000259
Abstract
The crystal structure of Na(+)546[Co(mal)2(en)],2H2O has been determined by the heavy-atom method from photographic data. Crystals are orthorhombic, space group P212121, with a= 13.46(2), b= 14.24(2)c= 7.344(10)Å, and Z= 4. Refinement by full-matrix least-squares gave R 0.05 for 838 observed reflections. The absolute configuration of the complex ion is Δ, in agreement with correlations from c.d. spectra. The tris-bidentate complex has an approximate two-fold axis with the two malonate ligands adopting boat conformations and folding towards each other while the ethylenediamine ligand is skewed oblique rather than parallel to the pseudo-three-fold axis of the anion. This result confirms the prediction that chair conformations are energetically unfavoured for malonate complexes and suggests the nature of the conformation interconversions shown by solution n.m.r. studies.Keywords
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