Tetraphenylarsonium 1,2,3,4,5-Pentakis(methylmercapto)cyclopentadienide

Article abstract of DOI:10.1021/ja00409a044

The title compound was prepared by reaction of stoichiometric amounts of sodium hydride, cyclopentadiene, and methyl disulfide in tetrahydrofuran.The title compound was characterized by NMR, IR, and cyclic voltammetry measurements.A three-dimensional crystal and molecular structure of <(C6H5)4As> has been determined by an X-ray diffraction study.The compound crystallizes in the centrosymmetric monoclinic space group P2₁/c 5_2h, No. 14> with a = 12.568 (2) Angstroem, b = 15.948(3) Angstroem, c = 17.523(3) Angstroem, β = 106.98 (1) deg, V = 3359.21 (10) Angstroem³, and ρ_calcd = 1.342 g cm^-3 for Z = 4.The structure was solved via the tangent formula and standard Fourier techniques and was refined by using full-matrix least-squares refinement to conventional discrepancy indices of R_F = 8.65percent and R_wF = 15.76percent for the 2652 independent data with ΔF/?(F₀) <= 10.0 and F₀ >= ?(F_o).All atoms with the exception of methyl hydrogens were located.The crystal consists of formula units of <(C6H5)4As(+)>, cations and anions being separated by normal van der Waals distances, as are formula units from each other.All distances and angles within the tetraphenylarsonium cation are normal.The methylmercapto groups of the 1,2,3,4,5-pentakis(methylmercapto)cyclopentadienide anion have their configurations relative to the cyclopentadienyl ring fixed by packing forces within the crystal.Distances and angles within the cyclopentadienyl ring are normal.The S-C distances within the anion are reduced from the sum of the covalent radii for sulfur and sp²-hybridized carbon which may indicate the possibility of multiple bonding.