MOLECULES WITH AN M4X4 CORE .10. FAILURE OF THE 1-1-1 TRICYCLOHEXYLPHOSPHINE-COPPER(I)-CHLORIDE COMPLEX TO FORM A TETRAMER - CRYSTAL-STRUCTURE OF DIMERIC (TRICYCLOHEXYLPHOSPHINE)COPPER(I) CHLORIDE, [(P(CHX)3)CUCL]2

(Tricyclohexylphosphine)copper(I) chloride crystallizes in the centrosvmmetric triclinic space group [formula omitted]and p(calcd)=1.34 g cm-3 for Z=1 (dimeric molecule). Diffraction data with 4.5° < 2θ < 40.0° (Mo Ka radiation) were collected with a Syntex P2, automated diffractometer, and the structure was solved via conventional Patterson, Fourier, and least-squares refinement techniques. All atoms (including hydrogens) were located directly, the final discrepancy indices being RF=4.9% and RwF=3.8% for those 1580 reflections with |Fo|> σ(|Fo|). The complex exists as the dimeric species [(P(cHx)3)CuCl]2—in sharp contrast to the tetrameric “cubane” or “step” structures found for all previously examined phosphine-copper(I) halide complexes with a 1:1 ratio of monodentate tertiary phosphine to copper (I). The dimeric molecule has precise C, symmetry. Each copper (I) atom is in trigonal-planar coordination to a phosphine ligand and two bridging chloride ions. Distances and angles within the coordination sphere are as follows: [formula omitted] Angles at the bridging chloride ligands are acute (<Cu-Cl-Cu=83.44 (7)°) despite the absence of a metal-metal bond (Cu—Cu=3.066 (1) υ); this is apparently due to intramolecular chlorine—chlorine repulsions (Cl⋯Cl'=3.439 (3) υ). © 1979, American Chemical Society. All rights reserved.