Stable, Two-Coordinate, Open Shell (d⁰—d⁹) Transition Metal Complexes

Well characterized, stable, two-coordinate, open shell transition metal complexes are currently very rare species. The small number of known examples are limited to the first row metals Cr → Ni and the majority are derivatives of amide or modified amide ligands. A characteristic feature of the compounds is the small number of electrons in their valence shells, as low as eight in the case of the Cr complexes. The compounds are very reactive toward protic reagents and nucleophiles. However, this and many other aspects of their chemistry have not been well developed. Current data available are limited to structural (X-ray and electron diffraction) and some spectroscopic and magnetic studies.