Redox Pairs of Diiron and Iron-Cobalt Complexes with High-Spin Ground States.

A series of iron and iron-cobalt bimetallic complexes were isolated: LFeCl (1), LFe (2), Li(THF)[LFeCl](Li(THF)[2-Cl]), LFeCoCl (3), and LFeCo (4), where L is a trianionic tris(phosphineamido)amine ligand. As elucidated by single-crystal X-ray diffraction studies and quantum-chemical calculations, the FeFe and FeCo complexes, 1 and 3, respectively, have weak metal-metal interactions (the metal-metal distances are 2.63 and 2.

Catalytic silylation of dinitrogen with a dicobalt complex.

A dicobalt complex catalyzes N2 silylation with Me3SiCl and KC8 under 1 atm N2 at ambient temperature. Tris(trimethylsilyl)amine is formed with an initial turnover rate of 1 N(TMS)3/min, ultimately reaching a turnover number of ∼200. The dicobalt species features a metal-metal interaction, which we postulate is important to its function.

Systematic variation of metal-metal bond order in metal-chromium complexes.

In the field of metal-metal bonding, the occurrence of stable, multiple bonds between different transition metals is uncommon, and is largely unknown for different first-row metals. Adding to a recently reported iron-chromium complex, three additional M-Cr complexes have been isolated, where the iron site is systematically replaced with other first-row transition metals (Mn, Co, or Ni), while the chromium site is kept invariant. These complexes have been characterized by X-ray crystallography.