Synthesis, crystal and molecular structures of an isomorphic N, S-bridged [Cu2(μ2-I)2(PPh3)2(μ2-N, S-pymSH)] dimer and S-bonded [CuX(η1-S-pymSH)(PPh3)2] monomers (X = Cl, Br)

Monoclinic crystals of [Cu-2(mu-I)(2)(PPh3)(2)(mu-N, S-pymSH)] center dot CH3CN) (1), were obtained by equimolar reaction of copper(I) iodide with pyrimidine-2-thione (pymSH), followed by the addition of triphenylphosphine (PPh3) in acetonitrile. Crystal data for 1: space group P2(1), Z = 2, a = 9.896, b = 18.378, c = 11.703 angstrom, beta = 101.73 degrees. It has an iodo-bridged Cu(mu-I)(2)Cu core and the pyrimdine-2-thione binds to both Cu centers via N, S-bridging across the Cu(mu-I)(2)Cu core. This N, S-bridging, a rare coordination mode for pyrimidine-2-thione, leads to a short Cu center dot center dot center dot Cu separation of 2.675(2) angstrom (sum of van der Waals radius of Cu atoms, 2.80 angstrom). The geometry around each Cu center is distorted tetrahedral with angles varying in the range, ca. 102-119 degrees. Copper(I) chloride and bromide also yielded monoclinic crystals of S-bonded tetrahedral monomers, [CuBr(pymSH)(PPh3)(2)] 2 and [CuCl(pymSH)(PPh3)(2)] 3. Crystal data for 2: space group P2(1)/n, Z = 8, a = 12.825, b = 43.122, c = 13.396 angstrom, beta = 90.79 degrees. Crystal data for 3: space group P2(1)/c, Z = 4, a = 14.340, b = 10.111, c = 24.200 angstrom, beta = 94.36 degrees. Compound 2 has two crystallographically independent molecules in crystal lattice. The (PNMR)-P-31 spectrum of 1 showed two signals for PPh3 ligands bonded to two Cu centers with different coordination cores: CuI2PN and CuI2PS. Both 2 and 3 showed one signal each for PPh3 in their (PNMR)-P-31 spectra.