Maria T. Andras

Reactivity of dithioacetic acid toward vanadocene: Crystal structure of the [(η5-C5H5)4V4(μ3-S)4] cluster

Abstract The reaction between vanadocene and dithioacetic acid gave the novel product [(η5-C5H5)4V4(μ3-S)4]. The single-crystal X-ray structure of this low-valent vanadium cluster has been determined. The crystallographic data are: monoclinic space group C2/c, a = 17.764(5), b = 8.119(2), c = 16.158(2) A, β = 116.65(2)°, V = 2083(2) A3, Z = 4. Refinement, using a data-to-parameter ratio of 12.0, converged with an unweighted discrepancy index of 4.99%. The molecule is located on a crystallographic two-fold rotation axis and consists of a central tetrahedron of vanadium atoms, each face of which is capped by a sulphur atom with vanadium-sulphur distances of 2.296(1) A. There is a cyclopentadienyl ring coordinated to each vanadium atom with vanadium-carbon distances ranging from 2.281(9) to 2.319(7) A. The vanadium-vanadium distance in [V4(μ3-S)4(η5C5H5)4] is 2.876(11) A and corresponds to a metal-metal bond order of 2/3. The cluster is paramagnetic; μeff = 2.65 μB·

Synthesis, structure, and characterization of Cu4S10(4-methylpyridine)4

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 Rw=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.

Room-Temperature Synthesis of CuInQ2 (Q = S or Se) in Non-Aqueous Solution Using an Organoindium Reagent

We have discovered a novel two-phase synthesis of CuInSe2 at 25 deg C from Cu2Se and (C5H5)3In in 4-methylpyridine (4-MePy). An analogous reaction to produce CuInS2 must be run at 140 deg C in refluxing 4-MePy in the presence of 2-mercaptopyridine. Microscopy of CuInSe2 produced at 25 deg C shows it to be platelet-shaped crystallites with an approximate particle size of 10 microns, less than 2 percent C and H, with a small amount of unidentified crystalline impurity. Our results demonstrate that it is possible to produce from solution a material that is ordinarily synthesized in bulk or films at much higher temperatures or using extraneous reagents and/or electrons.