Synthesis and structural characterization of a simple Cu(I) and an unexpected mixed-valence copper(I/II) complex with a supporting phosphinoferrocene amine ligand

• Cu-complexes with a phosphinoferrocene amine ligand were synthesized.
• The ligand coordinates Cu(I) as a P,N-chelating donor.
• Reaction of the ligand with CuCl produced a mixed-valence Cu(I/II) complex.
• All products were structurally characterized.

1′-(Aminomethyl)-1-(diphenylphosphino)ferrocene (1) reacts with [Cu(MeCN)4][BF4] in a 2:1 molar ratio to afford the chelate complex [Cu(1-κ2N,P)2][BF4] (2). A similar reaction of 1 with copper(I) chloride furnished an unexpected mixed-valence Cu(I)/Cu(II) octacopper complex, [Cu4(μ(P,N)-1)2(μ-Cl)5Cl(1H-κP)(H2O)]2 (3), comprising P,N-coordinated 1 and chloride ions as the bridging ligands, and N-protonated phosphinoamine 1H+ as a monodentate phosphine donor. The structures of 2·AcOEt and 3·10CHCl3 were determined by single-crystal X-ray diffraction analysis, and the redox behavior of 2 was examined by voltammetric techniques.

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