The molecular structure of the perchlorate of Eschenmoser's ‘pseudo-corrin’

Abstract

The crystal and molecular structure of a compound obtained from an unsuccessful attempt to effect the final stage of Eschenmoser's synthesis of corrin has been determined by three-dimensional X-ray diffraction methods in order to demonstrate the nature of the product which has a visible and ultraviolet spectrum very similar to that of a corrin nucleus. The product (I) is formed when its precursor reacts with the acetonitrile solvent instead of forming the corrin nucleus by an intramolecular ring closure, and is separated as the perchlorate. The odd alternate conjugate system in the molecule has the same number of the same types of atoms in the same order as has the corrin nucelus. However, the nitrogen atoms form two faces of the cobalt co-ordination octahedron, not the equator, and gross deviations from planarity in the conjugated system result from this.