MOLECULES WITH AN M4X4 CORE .11. UNEXPECTED ISOLATION OF THE CUBANE-LIKE ISOMER OF TETRAMERIC (TRIPHENYLARSINE)COPPER(I) IODIDE - CRYSTAL-STRUCTURE OF [(ASPH3)CUI]4.C6H6

Tetrameric (triphenylarsine)copper(I) iodide crystallizes from benzene as the 1:1 solvate [(AsPh3)CuI]4.C6H6. This species crystallizes in the centrosymmetric monoclinic space group p21/c with a = 14.605 (2) Å,b= 18.446 (3) Å, c = 28.524 (5) Å,β= 93.25 (1)Δ, K= 7672 (2) Å3 p(obsd) = 1.80g cm-3 and p(calcd) = 1.788 g cm-3 for formula weight 2064.874 and Z = 4. X-ray diffraction data were collected with a Syntex p21 four-circle automated diffractometer and the structure was solved via Patterson, Fourier, and least-squares refmernent techniques. All 90 nonhydrogen atoms were located accurately, the final discrepancy indices being RF = 6.6% and RwF = 4.9% for all 4857 reflections with 4Δ < 2θ < 35Δ (Mo Kα radiation). The CU4I4 core takes up a cubane-like geometry rather than the predicted step (or “chair”) structure. Copper-iodine bonds are 2.667 (2)-2.724 (2) Å in length, while copper-arsenic distances range from 2.366 (3) to 2.384 (3) Å. Intramolecular copper⋯copper contacts vary from 2.781 (3) to 2.900 (3) Å, while (nonbonding) iodine⋯iodine separations range from 4.314 (2) to 4.515 (2) Å. The possible approximate axis through the [(AsPh3)CuI]4 molecule is broken by minor rotations of the phenyl groups about their As-C(α) bonds. © 1979, American Chemical Society. All rights reserved.