Boris A. Kolesov

Triangular thiocomplexes of molybdenum : reactions with halogens, hydrohalogen acids and phosphines

Abstract The triangular (NH4)2Mo3S13·2H2O complex interacts with Cl2 and Br2 in CH3CN and with concentrated hydrohalogen acids HX (X = Cl, Br and I) retaining its Mo3(μ3-S)(μ-S2)34+ cluster fragment to produce the Mo3(μ3-S)(μ2-S2)3X62− complexes in high yields. IR and Raman spectra of the Mo3S7X62− complexes have been studied. Salts of Mo3S7X62− (X = Cl, Br) containing 92Mo, 100Mo and 34S isotopes and compounds with μ2-(32S-34S) ligands have been also synthesized. For Mo3S7Cl62−, an analysis of the normal vibrations has been performed. The Mo3S7X62− complexes (X = Cl, Br) interact with phosphines (PPh3 and dppe). The reactions proceed with elimination of the μ2-S2 sulfurs to form sulfides of the phosphines and the phosphine complexes Mo3S4X4·3PPh3 and Mo3S4X4·3dppe containing a Mo3S44+ cluster fragment. It has been shown, for the reaction of Mo3(μ3-34S)(μ2-32Se-34Sa)3Cl62− with PPh3, that it is the equatorial μ2-S2 sulfurs that are predominantly eliminated.

Triangular W3S74+ and W3S44+ complexes

Abstract Methods for the synthesis of triangular thiohalogenide complexes of tungsten W 3 S 7 X 4 (Xue5fbCl, Br) proceeding from metallic tungsten or WS 3 have been developed. Ways have been found for converting these polymeric complexes to triangular W 3 S 7 X 6 2− complexes which preserve the architecture of the W 3 (μ 3 -S)(μ 2 -S 2 ) 3 4+ cluster fragment. Heating W 3 S 7 X 4 in a PPh 4 X melt or in concentrated acids HX in the presence of Et 4 NX afforded PPh 4+ and Et 4 N + salts of W 3 S 7 X 6 2− (Xue5fbCl, Br). The structure of (Ph 4 P) 2 W 3 S 7 Br 6 ( III ) was established by X-ray diffraction analysis. The crystals of III are orthorhombic, a =18.082(2), b =25.834(3), c =27.370(2) A, Z =8, Pbca , R ( R w )=0.049 (0.055). The Et 4 N + salt of W 3 34 S 7 Br 6 2− has been obtained and a calculation of the normal vibrations has been performed for W 3 S 7 Br 6 2− . Interaction of W 3 S 7 Br 4 , with a KNCS melt or an aqueous solution of (NH 4 ) 2 S x involves transformation of the cluster fragment W 3 S 7 4+ to a W 3 S 4 4+ fragment to produce W 3 S 4 (NCS) 9 5− and W 3 S 4 (S 4 ) 3 (NH 3 ) 3 2− complexes. The structure of (NH 4 )(H)(H 2 O) 3 W 3 S 16 (NH 3 ) 3 ( VI ) was established by X-ray diffraction analysis. The crystals of VI are trigonal, a =12.508(1), c =10.112(1) A, Z =2, P 31 c , R ( R w )=0.029 (0.033).

High Proton Conductivity and Spectroscopic Investigations of Metal–Organic Framework Materials Impregnated by Strong Acids

Strong toluenesulfonic and triflic acids were incorporated into a MIL-101 chromium(III) terephthalate coordination framework, producing hybrid proton-conducting solid electrolytes. These acid@MIL hybrid materials possess stable crystalline structures that do not deteriorate during multiple measurements or prolonged heating. Particularly, the triflic-containing compound demonstrates the highest 0.08 S cm(-1) proton conductivity at 15% relative humidity and a temperature of 60 °C, exceeding any of todays commercial materials for proton-exchange membranes. The structure of the proton-conducting media, as well as the long-range proton-transfer mechanics, was unveiled, in a certain respect, by Fourier transform infrared and (1)H NMR spectroscopy investigations. The acidic media presumably constitutes large separated droplets, coexisting in the MIL nanocages. One component of proton transfer appears to be related to the facile relay (Grotthuss) mechanism through extensive hydrogen-bonding interactions within such droplets. The second component occurs during continuous reorganization of the droplets, thus ensuring long-range proton transfer along the porous structure of the material.

Synthesis, structure, vibrational spectra and chemical properties of the triangular molybdenum and tungsten complexes M3(μ3-S)(μ2-SSe)3X62− (M = Mo, W; X = Cl, Br)

Abstract Salts containing M3(μ3-S)(μ2-S2)3X62− (M = Mo, W; X = Cl, Br) anions interact with SePPh3 upon heating in acetonitrile to form SPPh3 and M3(μ3-S)(μ2-SSe)3X62−. The stereochemisty of this reaction has been studied. In the reaction of SePPh3 with Mo3(μ3-34S)(μ2-34Sa32Se)3X62− replacement of the equatorial sulfur atoms takes place, and 32SPPh3 and Mo3(μ3-34S)(μ2-34SaSee)3X62− are produced. The structure of (PPh3Et)2Mo3(μ3-S)(μ2-SSe)3Cl6 (I) was established by X-ray diffraction analysis. The crystals of I are triclinic, space group P 1 (a = 13.547(2), b = 13.755(2), c = 15.736(3) A; α = 101.79(1), β = 97.71(1), γ = 110.49(1)°, Z = 2). A total of 5721 independent reflections has been collected on an automated diffractometer, and the structure was solved to R = 0.051 (Rw = 0.062). The selenium atoms are essentially in the plane of the Mo3 triangle. The Sue5f8Se distances are 2.157(5)–2.163(4) A. Complex I is the first compound containing a Sue5f8Se ligand that has been structurally characterized. IR and Raman spectra of M3S4Se3X62− have been studied. For Mo3S4Se3Cl62− an analysis of the normal vibrations has been performed. The force constant of the Sue5f8Se bond in complex I is 2.3 mdyn/ A. Heating of (Et4N)2Mo3S4Se3Br6 under vacuum at 450 °C gave rise to MoSSe.

Synthesis and vibrational (IR and Raman) spectroscopic study of triangular thio-complexes [Mo3S13]2− containing 92Mo, 100Mo and 34S isotopes

Abstract The triangular anionic thio-complex [Mo3S13]2− has been obtained by the reaction of the triangular molybdenum thiobromide Mo3S7Br4 with an aqueous solution of Sx2−. Starting from compounds containing 92Mo, 100Mo and 34S isotopes, the following thio-complexes have been obtained: [92Mo3S13]2−, [100Mo3S13]2−, [Mo334S13]2-, [Mo3(μ3-S)(μ2-S34S)3(34S2)3]2− and [Mo3(μ3-34S)(μ2-34SS)3(S2)3]2−. Along with the nucleophilic substitution of the Br ligands by the terminal S2 ligands, elimination—addition of sulphur in μ2-S2 ligands also takes place. This allows preparation of thio-complexes containing μ2-34S32S ligands. IR and Raman spectra of the thio-complexes have been studied, normal vibrations have been calculated and the bond force constants determined.

Synthesis of isotopomeric binuclear thio complexes of molybdenum and tungsten and the study of their vibrational spectra

Abstract Alkylammonium salts, W 2 34 S 4 X 4 2− (X = Cl, Br), M 2 34 S 4 Br 8 2− (M = Mo, W) and Mo 2 34 S 6 O 2 2− , have been obtained from 34 S 8 . IR and Raman spectra of these compounds have been studied and the normal vibrations calculated. A number of vibrations involving sulphur atoms [for example v (Mue5fbS), v (Sue5f8S)] are characteristic, which allows vibrational spectroscopy to be used to study the changes occurring in the metal-sulphur containing fragments. The interaction of W 2 (μ 2 -S)(μ 2 -S 2 )Br 8 2− with 34 S 8 was shown to produce W 2 (μ 2 -S 2 ) 2 Br 8 2− . The reaction of Mo 2 (μ 2 - 34 S 2 ) 2 Cl 4 C 4/2 with S x 2− results in the replacement of 34 S by 32 S to produce the Mo 2 (μ 2 -S 2 ) 2 (S 2 ) 4 2− complex.