Synthesis, characterization, structures and reactivities of dinuclear copper(I) complexes of three new binucleating hexadentate ligands having N2P4 or N2As4 donor sites

Abstract

Three new binucleating hexadentate ligands having N₂P₄ or N₂As₄ donor sites, viz. N,N,N′,N′-tetrakis-[2-(diphenylphosphino)ethyl] ethane-1,2-diamine (L¹), its arsine analogue (L²) and 1,3-bis{bis[2-(diphenylphosphino)ethyl]aminomethyl}benzene (L³) have been prepared. The ligands react with [Cu(PPh₃)₃Cl] to give the dinuclear four-co-ordinate copper(I) complexes [Cu₂(L¹)(PPh₃)₂Cl₂], [Cu₂(L²)(PPh₃)₂Cl₂] and [Cu₂(L³)Cl₂]. With [Cu(NCMe)₄][ClO₄] the ligands yielded the three-co-ordinate dinuclear complexes [Cu₂L][ClO₄]₂(L = L¹, L² or L³), which on treatment with NaN₃. NH₄NCS, KOH or NaBH₄(L = L¹ or L³) gave dinuclear four-co-ordinate copper(I) complexes [Cu₂L(X)₂](X = N₃, NCS, OH or BH₄)via elimination of perchlorate and co-ordination of X. For the tetrahydroborato complexes, two hydrogen atoms of each BH₄^– ligand were co-ordinated to separate copper(I) centres. All the new ligands and complexes were characterized on the basis of elemental analysis, molar conductivity, IR spectra and ¹H, ¹³C-{¹H}, ¹¹B-{¹H} and ³¹P-{¹H} NMR spectral data. The molecular structures of [Cu₂(L¹)(PPh₃)₂Cl₂]1 and [Cu₂(L³)Cl₂]3 were established by single-crystal X-ray diffraction [crystal data: 1, C₉₄H₉₀Cl₂Cu₂N₂P₆, triclinic, space group P, a= 11.711(2), b= 18.731(3), c= 10.080(1)Å, α= 91.22(1), β= 107.45(1), γ= 78.11(1)°, Z= 1, final R factor 0.040 (R′= 0.046) for 3715 observed reflections; 3, C₆₄H₆₄Cl₂Cu₂N₂P₄, triclinic, space group P, a= 12.922(4), b= 19.161(1), c= 12.777(3), Å, α= 93.11(1), β= 111.85(2), γ= 84.69(1)°, Z= 2, final R factor 0.042 (R′= 0.046) for 5684 observed reflections].