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)

摘要

Monoclinic crystals of [Cu2(μ-I)2(PPh3)2(μ-N, S-pymSH)] · 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 P21, Z = 2, a = 9.896, b = 18.378, c = 11.703 ?, β = 101.73°. It has an iodo-bridged Cu(μ-I)2Cu core and the pyrimdine-2-thione binds to both Cu centers via N, S-bridging across the Cu(μ-I)2Cu core. This N, S-bridging, a rare coordination mode for pyrimidine-2-thione, leads to a short Cu···Cu separation of 2.675(2) ? (sum of van der Waals radius of Cu atoms, 2.80 ?). The geometry around each Cu center is distorted tetrahedral with angles varying in the range, ca. 102–119°. 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 P21, Z = 8, a = 12.825, b = 43.122, c = 13.396 ?, β = 90.79°. Crystal data for 3: space group P21/c, Z = 4, a = 14.340, b = 10.111, c = 24.200 ?, β = 94.36°. Compound 2 has two crystallographically independent molecules in crystal lattice. The 31P NMR 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 31P NMR spectra.