Transtion-metal dithiolene complexes. Part XIV. Five-co-ordinate phosphine and phosphite adducts of cobalt and iron bis(diaryl-1,2-dithiolenes)

Abstract

The phosphine and phosphite adducts of cobalt and iron bis(diaryl-1,2-dithiolene), [M(PR₃)(S₂C₂Ar₂)₂]⁰, (M = Co or Fe; R = Et, CH₂CH₂CN, Ph, OPh, or NMe₂; Ar = Ph, 4-Me·C₆H₄, 2- 3- or 4- MeO·C₆H₄, 3,4-CH₂O₂C₆H₃, or 2,5-(MeO)₂C₆H₃) have been prepared. The voltammetry of these complexes shown that they are part of at least a three- and possibly a four-membered electron transfer series, [M(PR₃)(S₂C₂Ar₂)₂]^z(z=+1, 0, –1, or –2. The half-wave potentials for the couple [M(PR₃)(S₂C₂Ar₂)₂]^z+ e^–⇌[M(PR₃)(S₂C₂Ar₂)₂]^z-1 depend on the nature of the substituents R and Ar. [Co(PEt₃){S₂C₂(4-MeO·C₆H₄)₂}₂] X (X = PF₆ or BPh₄)[Co{P(NMe₂)₃}{S₂C₂(4-Me.C₆H₄)₂}₂][BPh₄] and [Buⁿ₄N][Co{P(CH₂CH₂CN)₃}S₂ C₂Ph₂)₂] have been isolated and characterised, and there is spectral evidence for [Fe{P(NMe₂)₃}{S₂C₂(4MeO.C₆H₄)₂}₂]⁺, [Fe{P(CH₂CH₂CN)₃}S₂C₂Ph₂)₂]^– and [Fe{P(OPh)₃}(S₂C₂Ph₂)₂]^–.