Structurally diversified neutral copper(I) isocyanide complexes: mono- and bi-nuclear complexes from the reaction of copper(I) halides with p-tolyl isocyanide

Abstract

The reaction of copper(I) iodide with p-tolyl isocyanide (RNC) led to different compounds depending on the stoicheiometric ratio and the presence of ancillary ligands. A large excess of RNC in the presence of NaBPh₄ yields the complex [Cu(RNC)₄]BPh₄, (2)[ν(CN)(Nujol)2 147 cm^–1]. Using a lower RNC:Cu ratio, the neutral complex [CuI(RNC)₃], (3)[ν(CN)(Nujol) broad band centred at 2 135 cm^–1] was isolated. In the presence of 2,2′-bipyridine (bipy) the mononuclear complex [CuI(bipy)(RNC)], (4)[ν(CN)(Nujol) 2 124 cm^–1], was isolated, while the use of a monodentate sterically demanding ligand, 1-benzyl-2-phenylbenzimidazole (bpbzim), afforded the asymmetric binuclear complex [Cu₂(µ-I)₂(bpbzim)₂(RNC)₂], (5)[ν(CN)(Nujol) 2 127 cm^–1][Cu ⋯ Cu 3.362(2), Cu–I 2.697(2) and 2.801 (2)Å]. The reaction of CuCl in tetra-hydrofuran with RNC led to the analogous binuclear complex [Cu₂(µ-Cl)₂(RNC)₄], (6)[ν(CN)(Nujol) 2 137 and 2 159 cm^–1][Cu ⋯ Cu 3.234(1)Å], having like (5) a slightly asymmetric bridged structure [Cu–Cl 2.382(1) and 2.419(1)Å]. Crystallographic details: complex (3), space group P2₁/c(monoclinic), a= 11.022(3), b= 11.288(2), c= 20.363(5)Å, β= 102.52(2)°, Z= 4, R 0.045 (R′= 0.050) for 1 831 observed reflections; (4), space group P(triclinic), a= 11.226(3), b= 11.935(3), c= 9.011(2)Å, α= 110.08(3), β= 101.07(3), γ= 80.22(3)°, Z= 2, R 0.041 (R′= 0.048) for 2 291 observed reflections; (5), space group P(triclinic), a= 12.526(2), b= 10.257(2), c= 11.144(3)Å, α= 109.16(2), β= 114.92(2), γ= 81.94(2)°. Z= 1, R 0.041 (R′= 0.038) for 2 131 observed reflections; (6), space group P2₁/n(monoclinic), a= 21.041 (4), b= 6.325(1), c= 13.184(2)Å, β= 104.28(1)°, Z= 2, R 0.043 (R′= 0.050) for 2 750 observed reflections.