Crystal and molecular structure of methyltriphenylphosphonium hexa-iodotetracuprate(I)

Abstract

The crystal structure of the title compound has been determined from single-crystal X-ray diffraction data by conventional methods. The yellow complex crystallises in rhombohedral space group Rc, with Z= 2 in unit cell of dimensions a=b=c= 15.603(2)Å, α=β=γ= 53.133(2)°. Full-matrix least-squares refinement returned a final R factor of 0.038 for 1 206 reflections. The complex has overall C_3v symmetry, with the [Ph₃MeP]⁺ ion adopting a ‘propeller-like’ conformation and the [Cu₄I₆]^2– ion forming a tetrahedron of copper atoms with iodine atoms displaced from the centre of each edge. Thus each copper atom has approximately trigonal planar co-ordination and is bridged by three iodine atoms. Within the crystal alternate anions have an inverted core of copper atoms whilst Still accommodating the same iodine atoms on tetrahedron edges. Cu–I bond distances range from 2.539(5) to 2.638(5)Å, and Cu–I–Cu bond angles are 63.9(2) and 65.2(2)°. The non-bonded Cu ⋯ Cu separations of the Cu₄ tetrahedron are 2.742(7) and 2.757(7)Å. The observed structure is consistent with that previously suggested on the basis of i.r, Raman, and n.q.r. studies.