ANION DESIGN BY CHOICE OF CATION - ISOLATION OF A DINUCLEAR CHLOROCUPRATE(I) ANION CONTAINING TRIGONALLY COORDINATED COPPER(I) USING THE TETRAETHYLPHOSPHONIUM CATION

A centrosymmetric di-mu-chloro-dichlorodicuprate(I) ion, [Cu2Cl4]2-, h as been prepared by selecting the tetraethylphosphonium cation as coun ter-ion, on the basis of its size in comparison with those of related symmetrically substituted phosphonium and ammonium cations. The copper (I) centres in [Cu2Cl4]2- exhibit distorted trigonal coordination and the anion can be seen as a loose association of [CuCl2]- moieties, in which the Cu-Cl bonds are 2.112(3) and 2.136(3) angstrom, joined by tw o long Cu ... Cl interactions of 2.922(3) angstrom. The Cu ... Cu and Cl ... Cl separations are 3.515(2) and 3.722(5) angstrom, respectively . [P(C2H5)4]2[Cu2Cl4] crystallizes in space group P2(1)/n with a = 11. 881(4), b = 7.976(3), c = 14.296(2) angstrom, beta = 112.46(2)-degrees , at - 150-degrees-C, and Z = 2. Full-matrix least-squares refinement yielded a final R = 0.051 (R(w) = 0.066) for 109 parameters and 1266 o bserved reflections.