Reactivity of Cu(I) Compounds towards Ethylenediamine and Dimethylformamide: Crystal Structure of CuCl(PiPr3)n (n=1, 2), CuX(PPh3)(en)2 (X=Cl, Br) and CuX(PPh3)(dmf)

Abstract

The synthesis of several phosphine Cu(I) complexes is reported, and their reactivity towards the solvents ethylenediamine (en) and dimethylformamide (dmf) has been investigated. CuX(PPh3) [X = Cl (1), Br (2)], CuCl(PCy3) (3) and CuCl(PiPr3)n [n = 1 (4), 2 (5)] were prepared according to adapted literature procedures. The complexes CuCl(PiPr3)n were obtained in crystalline form from a hexane solution at -70 °C and structurally characterized for n = 1 and 2. Copper halide complexes of PCy3 (3) and PiPr3 [n=1 (4)] gave colorless solutions in both en and dmf indicating the absence of Cu(II) ions. CuCl(PiPr3)2 is stable in dmf solutions. By contrast, the complexes CuX(PPh3) (X = Cl, Br) dissolve with blue color in en and with greenish-yellow color in dmf at higher temperatures under inert gas indicating a redox process affording Cu(II). At room temperature colorless crystals of CuX(PPh3)(en)2 [X = Cl (6), Br (7)] and CuX(PPh3)(dmf) [X = Cl (8), Br (9)] were isolated from the solutions and analyzed by single-crystal X-ray diffraction.