Crystal and molecular structure of di-iodotetrakis-(p-tolylisocyano)cobalt(II), (MeC6H4NC)4Col2

Abstract

The crystal structure of di-iodotetrakis-(p-tolylisocyano)cobalt(II) has been elucidated by an X-ray analysis based on photographic data, and refined to R 8·7%. The space group I4₁/a here requires that the molecular symmetry in the crystal is (S₄). Iodine atoms occupy axial trans positions of the octahedral cobalt valencies, while the four p-tolylisocyano-groups occupy the equatorial positions; the axes of the long organic ligands deviate alternately in opposite directions from the mean equatorial plane by ca. 5°. The Co–l distance of 2·690 ± 0·006 Å is unusually long, while the Co–C distance of 1·81 ± 0·04 Å is shorter than expected for a single bond, but not significantly different from that found in (MeNC)₅CoClO₄. Other distances in the organic ligand are as expected. In the crystal, the benzene rings of different molecules stack above one another in a four-fold screw arrangement parallel to c, creating channels between the long organic ligands ca. 5 Å in diameter.