The X-ray structure analysis of anhydrous heptamethyl dicyanocobyrinate (cobester)

Abstract

The X-ray structure analysis of the anhydrous form of heptamethyl dicyanocobyrinate (cobester) was carried out as part of a collaborative investigation with Battersby and co-workers and compared with that of the hydrated form.

The anhydrous form crystallises in the orthorhombic space group P2₁2₁2₁ with cell dimensions a= 18.931(6), b= 18.960(5), c= 15.643(6)Å and one molecule in the asymmetric unit. The structure was solved by a combination of Patterson and direct methods and refined to R= 0.132. Several of the side-chains were disordered. The paper describes the structural details and gives a comparison with other relevant structures retrieved from the Structural Database. The best mean values for the corrin nucleus are given and a summary table of the conformations taken up by the pyrrole rings in various cobalt-corrin systems is presented.