Zinc-rich compounds of iron and cobalt: Formation of [Fe2Znn] (n = 2–4) and [Co2Zn3] cores

Abstract

The reactions of heteroleptic GaCp*/CO containing transition metal complexes of iron and cobalt, namely [(CO)₃M(μ₂-GaCp*)_mM(CO)₃] (Cp* = pentamethylcyclopentadienyl; M = Fe, m = 3; M = Co, m = 2) and [Fe(CO)₄(GaCp*)], with ZnMe₂ in toluene and the presence of a coordinating co-solvent were investigated. The reaction of the iron complex [Fe(CO)₄(GaCp*)] with ZnMe₂ in presence of tetrahydrofurane (thf) leads to the dimeric compound [(CO)₄Fe{μ₂-Zn(thf)₂}₂Fe(CO)₄] (1). Reaction of [(CO)₃Fe(μ₂-GaCp*₃)Fe(CO)₃] with ZnMe₂ and stoichiometric amounts of thf leads to the formation of [(CO)₃Fe{μ₂-Zn(thf)₂}₂(μ₂-ZnMe)₂Fe(CO)₃] (2) containing {Zn(thf)₂} as well as ZnMe ligands. Using pyridine (py) instead of thf leads to [(CO)₃Fe{μ₂-Zn(py)₂}₃Fe(CO)₃] (3) via replacement of all GaCp* ligands by three{Zn(py)₂} groups. In contrast, reaction of [(CO)₃Co(μ₂-GaCp*)₂Co(CO)₃] with ZnMe₂ in the presence of py or thf leads in both cases to the formation of [(CO)₃Co{μ₂-ZnL₂}(μ₂-ZnCp*)₂Co(CO)₃] (L = py (4), thf (5)) via replacement of GaCp* with {Zn(L)₂} units as well as Cp* transfer from the gallium to the zinc centre. All compounds were characterised by NMR spectroscopy, IR spectroscopy, single crystal X-ray diffraction and elemental analysis.