Yu.L. Slovokhotov

Layered compounds assembled from molybdenum disulfide single-layers and alkylammonium cations

Abstract Intercalation compounds A x MoS 2 have been obtained by restacking aqueous MoS 2 dispersions in the presence of A-alkylammonium cations (A=R 4 N + or R(CH 3 ) 3 N + ). Varying the experimental conditions, the negative charge of the MoS 2 single-layers in the dispersions can be modified, which allows to control the content and packing geometry of the A guest layers in the resulting intercalation compounds. The value of the negative charge kept on the MoS 2 host layers of the intercalation compounds determines the degree of in-layer distortion of their Mo sublattice.

From single-layer dispersions of molybdenum disulfide towards ternary metal sulfides: incorporating copper and silver into a MoS2 matrix

Abstract Interaction of MoS 2 single-layer dispersions with Cu(II) or Ag(I) salts results in formation of ternary metal sulfides. Upon this, reduction of Cu(II) to Cu(I) and reduction of part of Ag(I) to Ag(0) occur. The structural features of the compounds are discussed on the basis of XRD, electron diffraction, EXAFS and XPS data.

Synthesis and X-ray structure of a novel 12-nuclear cluster Pd12(CO)12(PBun3)6

Abstract A novel dodecanuclear cluster compound Pd12(CO)12(PBun3)6 (I) was obtained by a mild oxidation of the known Pd10(CO)12(PBun3)6 and Pd4(CO)5(PBun3)4 clusters with Me3NO and by a reaction of Pd10(CO)12(PBun3)6 with binuclear Pd2(DBA)3 (where DBA=dibenzylideneacetone) under Ar. A single crystal X-ray diffraction study of (I) (P 1 , Z=2, R=0.065 on 4452 reflections) revealed two independent hexacapped distorted octahedra of Pd atoms positioned on the crystallographic inversion centres, with six μ2- and six μ3-CO ligands as well as six PBun3 ligands bonded to the capping palladium atoms.

OPTICALLY ACTIVE PENTANUCLEAR WING-TIP BUTTERFLY HETEROTRIMETALLIC CLUSTERS

The pentanuclear heterotrimetallic clusters of formula Fe 3 MC(CO) 12 M′L {M = Co, M′ = Au, L = PPh 3 ( XIV ); M = Co, M′ = Pd. L = η 3 -C 3 H 5 ( XV ); M = Co, M′ = Pd, L = η 3 - β -pinenyl, C 10 H 15 ( I ); M = Rh, M′ = Au, L = PPh 3 ( XVI ); M = Rh, M′ = Pd. L = η 3 -C 3 H 5 ( XVII ); M = Rh, M′ = Pd, L = η 3 -C 10 H 15 ( II )} have been obtained by the have been obtained by the addition of corresponding M′L fragments to heterometallic butterfly [Fe 3 MC(CO) 12 ] − , where M = Co ( XI ) or Rh ( X ); the butterfly XI has been isolated in reductive degradation of Co-containing clusters [Fe 3 Co 3 C(CO) 15 ] − or [Fe 4 CoC(CO) 14 ] − . The X-ray crystal structures of XIV and XV have been determined. Both structures have approximately the same pentanuclear heterotrimetallic cluster cores with M′L groups in bridging position linking wing tips. According to the refinement data, the Co atoms in XIV and XV are placed in the basal position of the butterfly. EXAFS data for XV suggest a structural flexibility of the metal core in solution. Absorption (AB) and circular dichroism (CD) spectra of two optically active clusters I and II with the same ‘wing-tip’ butterfly structure were investigated and compared with those for the starting [Pd( η 3 - β -C 10 H 15 )Cl] 2 chiral complex. The noticeable Cotton effects (CE) in the CD spectra induced in electron transitions of cluster metallochromophores demonstrate a strong manifestation of the vicinal optical activity.

Distortion of MoS2 host layers in intercalation compounds with various guest species: correlation with charge transfer

Abstract The MoS 2 host layers in various intercalation compounds freshly prepared from single-layer dispersions are substantially distorted compared to those in parent crystalline 2 H -MoS 2 . The coordination number for the Mo–Mo sphere ( d ∼3.2 A) obtained from Mo K-edge EXAFS data can be used as a convenient parameter to estimate qualitatively the degree of distortion, which is shown to correlate fairly with the residual negative charge kept by the host layers.

Chiroptical properties of heterotrimetallic ‘wing-tip’ butterflies; synthesis and crystal structure of (μ-H)Ru2Fe2PdC(CO)12 (η3-ß-C10H15)

Abstract HRu2Fe2PdC(CO)12 (η3-s-C10H15) cluster was prepared in the reaction of (Et4N) [HFe2Ru2C(CO)12] with [Pd(η3-s-C10H15)Cl]2. X-ray structural study of HRu2Fe2PdC(CO)12 (η3-s-C10H15) (where s-C10H15 is s-pinenyl) revealed a wing-tip butterfly geometry of the metal core and (1R, 2S, 3S, 5R) absolute configuration for both crystallography independent molecules in the crystal. Chiroptical properties of this cluster are compared with other clusters containing a Pd(η3-s-C10H15) fragment and discussed.

Thermal transformations of nanocomposite material consisting of molybdenum disulfide and nickel hydroxide layers

Abstract The structure of Ni(OH)2/MoS2 nanocomposite material obtained via MoS2 single-layer dispersion and the products of its annealing in the 100–400°C temperature range were studied using X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). The transformation of the initial MoS2 superlattice structure with Mo–Mo bonding to the usual structure with unique Mo–Mo distance was found to occur upon annealing. The decomposition of two-dimensional Ni(OH)2-like species in the interlayer space of MoS2 at 400°C leads to complete substitution of O by S in the Ni local environment.

EXAFS study of the M0.5(OH)x(H2O)yMoS2 intercalated complexes

Synchrotron EXAFS spectra (Novosibirsk VEPP-3 storage ring, 2.5 ReV, 120 mA, Si[111] monochromator) of the noncrystalline intercalates Ni 0.5 (OH) x (H 2 O) y MoS 2 (1), Co 0.5 (OH) x (H 2 O) y MoS 2 (2), Fe 0.5 (OH) x (H 2 O) y MoS 2 (3), and (Ni,La) z (OH) x (H 2 O) y MoS 2 (4), prepared by the ion-exchange reaction of Li x MoS 2 with the corresponding aqua ions in water, exhibit two closest coordination shells M-O and M...M. The spectra of (1)-(3) together with their X-ray powder data fit the structure of alternating MoS 2 and M(OH) 2 hexagonal layers. The M-O (2.05-2.20 A) and M...M distances (3.11-3.23 A) in (1)-(4) agree well with the known crystal structures of M(OH) 2

Laser-Electron X-Ray Generator

The possibility of developing a laser-electron x-ray generator based on the Thomson scattering of laser radiation by relativistic electrons and prospects for its application are considered. In its specifications (brightness, average intensity, and dimensions), as well as its construction and operation cost, such a generator is intermediate between x-ray tubes and synchrotron sources. The configuration of channels and experimental stations intended for applications of an x-ray laser-electron generator in studies of the elemental composition and structure of materials is discussed.

Cluster approach to the synthesis of ternary metal sulfides: Molybdenum disulfide single layers as a precursor

The reactivity of negatively charged (MoS2)x− layers in aqueous single-layer dispersions resembles that of molecular Mo-S cluster compounds. These layers form covalent bonds with metal (M) cations (M=Cu, Ag, Pb, Cd, Hg, Pd), giving rise to ternary metal sulfides MzMoS2 whose Mo network contains direct Mo-Mo bonds.