The title compound, Cu4S10(4-methylpyridine)4 · 4-methylpyridine was prepared by three different reactions: the oxidation of copper power by sulfur and the reaction of copper (I) sulfide (or CuBr-SMe2) with cues sulfur, both in the coordinating solvent, 4-methylpyridine. Red crystals of the compound obtained by layering with hexans were subjected to single crystal X-ray diffraction. The structure was refined toR=0.026 and R w =0.036 in a space groupP1bar (No. 2), withZ=2,a=13.983 (2) A,b=15.384( 2) Å,c=9.660 (1) Å, α = 93.87 (1)°,β=93.38 =γ=(1)°,V=2037.9 (9) Å3. The commpound has approximate S4 symmetry and consists of two pentasuffide chains linking four Cu(I) ions, each with a coordinating 2-methylpyridine. The infrared spectrum was dominated by absorption due to coodinated 4-methylpyridine with several low-energy peaks attributable to S-S stretches, which were also observed by Raman spectroscopy. A featureless electronic absorption spectrum yielded a single peak in the mar ultraviolet upon computer enhancement (λ=334 nm, ε = 10,000), most likely an intraligand transition. Cyclic voltammetry indicates that the polysulfide complex undergoes irreversible oxidation and reduction at +0.04 and −0.34 V vs. SCR respectively, at NS K in 4-methylpyridine when swept at 20 mV/sec. The electrochemical behavior was unvaried even at sweep rates as high as 100 V/sec.

Neutral metal dithiocarbamate complexes (M(NR2CS2)X) are well-known precursors to metal sulfides, a class of materials with numerous technological applications. We are involved in a research effort to prepare new precursors to metal sulfides using simple, reproducible synthetic procedures. We describe the results of our synthetic and characterization studies for M = Fe, Co, Ni, Cu. and In. For example, treatment of metallic indium with tetramethylthiuram disulfide (tmtd) in 4-methylpyridine (4-Mepy) at 25 deg C produces a new homoleptic indium (III) dithiocarbamate, In(N(CH3)2CS2)3(I), in yields of over 60 percent. The indium (III) dithiocarbamate was characterized by X-ray crystallography; (I) exists in the solid state as discrete distorted-octahedral molecules. Compound (I) crystallizes in the P1bar (No. 2) space group with lattice parameters: a = 9.282(1) A, b = 10.081(1) A, c = 12.502 A, alpha = 73.91(1) deg, beta = 70.21(1) deg, gamma = 85.8(1)deg, and Z = 2. X-ray diffraction and mass spectral data were used to characterize the products of the analogous reactions with Fe, Co, Ni, and Cu. We discuss both use of dithiocarbamates as precursors and our approach to their preparation.

Three copper systems with relevance to materials technology are discussed. In the first, a CuS precursor, Cu4S10(4-methylpyridine)4 (4-MePy), was prepared by three routes: reaction of Cu2S, reaction of CuBr·SMe2 and oxidation of copper powder with excess sulfur in 4-methylpyridine by sulfur. In the second, copper powder was found to react with excess thiourea (H2NC(S)NH2) in 4-methylpyridine to produce thiocyanate (NCS-) complexes. Three isolated and characterized compounds are: Cu(NCS)(4-MePy)2, a polymer, [4-MePy·H][Cu(NCS)3(4-MePy)2], a salt, and t-Cu(NCS)2(4-MePy)4. Finally, an attempt to produce a mixed-metal sulfide precursor of Cu and Ga in N-methylimidazole (N-Melm) resulted in the synthesis of a Cu-containing polymer, Cu(SO4)(N-MeIm). The structures are presented; the chemistry will be briefly discussed in the context of preparation and processing of copper-containing materials for aerospace applications.