A journey through ternary lead chlorido tungstates by thermal scanning

The reaction of WCl₆with lead powder affords six new compounds, all monitored in one DSC run, and characterized by XRD techniques.

From WCl6 to WCl2: Properties of Intermediate Fe-W-Cl Phases

Phenomenological studies of WCl6 reduction with transition metal powders M = Mn, Fe, and Co have been recently reported. These reactions involve a series of reductive intercalation steps of M atoms into layered tungsten chloride arrangements, followed by exsolution of MCl2. In the series M = Fe, the presence of divalent iron is evidenced for Fe(x)WCl6, FeW2Cl10, Fe2W2Cl10, and (Fe,W)Cl2 by Mössbauer spectroscopy. Magnetic properties are reported. Bonding characteristics between tungsten atoms in edge-sharing [W2Cl10](n-) bioctahedra reveal that a double bond can be addressed to FeW2Cl10. A similar situation appears for Fe2W2Cl10, due to the localized and thus nonbonding character of the two electrons in the δ orbitals of this compound.

Edge-bridged octahedral tungsten-oxygen-chlorine clusters: synthesis and characterization of two D(3d)-symmetric [W(6)O(6)Cl(12)](2-) isomers and [W(6)O(7)Cl(11)](3-)

Initial access to the chemistry of hexanuclear tungsten oxohalide clusters is provided through the reduction of WOCl(4) with bismuth metal at 360 degrees C. Reactions targeting W(6)O(6)Cl(10) produce an amorphous black solid, which, upon treatment with concentrated aqueous HCl, releases the edge-bridged octahedral cluster [alpha-W(6)O(6)Cl(12)](2-) into solution. The cluster exhibits a D(3d)-symmetry structure in which the six oxygen atoms bridge the edges between two opposing triangular faces of a trigonally compressed W(6) octahedron. Reactions incorporating additional bismuth metal yield a mixture of soluble clusters, including a 5:7 ratio of [alpha-W(6)O(6)Cl(12)](2-) and another D(3d)-symmetry isomer, [beta-W(6)O(6)Cl(12)](2-). The latter species displays a different core structure, in which the six oxygen atoms are situated on the edges comprising two opposing triangular faces of a trigonally elongated W(6) octahedron. Isolated as the BuN(+) salts, the two isomers can be separated by a process relying on the differences in crystal morphology. Cyclic voltammetry of acetonitrile solutions shows two reversible one-electron reductions for each cluster, the alpha isomer being slightly more easily reduced. Density functional theory calculations indicate that the two isomers of [W(6)O(6)Cl(12)](2-) are nearly identical in energy, with the beta isomer lying just 1.4 kcal/mol below the alpha isomer. The other major product isolated from the reaction with additional bismuth is [W(6)O(7)Cl(11)](3-), a cluster at least formally related to [beta-W(6)O(6)Cl(12)](2-) by substitution of an O(2)(-) ion for a core Cl(-) ion. In acetonitrile solution, this cluster displays a single reversible one-electron reduction. It is anticipated that the reactions elaborated here will lead to a general method for synthesizing metastable metal oxohalide clusters.

Excision of zirconium iodide clusters from highly cross-linked solids

Highly cross-linked cluster precursors KZr6I14B, Zr6I12B, KZr6I14C, and Zr6I12C were, successfully excised in deoxygenated water, and the resulting red aqueous solutions of clusters exhibit better kinetic stability with respect to decomposition than their chloride and bromide analogues. On traversing the Cl-->I series, NMR measurements show increasing deshielding of the interstitial atoms (Z = B, C) in Zr6ZX12 clusters and cyclic voltammetry reveals increasingly positive reduction potentials for the [(Zr6BX12)(H2O)6]+ ions. Several new cluster complexes have been crystallized from aqueous or methanolic solutions. Crystallographic data for these compounds are as follows: [(Zr6BI12)(H2O)6]Ix11.7(H2O) (1), triclinic, P1, a = 10.2858(7) A, b = 11.3045(8) A, c = 20.808(1) A, alpha = 77.592(1) degrees, beta = 79.084(1) degrees, gamma = 77.684(1) degrees, Z = 2; [(Zr6BI12)]+[I(CH3OH)6]- (2), hexagonal, R3, a = 17.706(1) A, c = 13.910(1) A, Z = 3, [(Zr6CI12)(H2O)6]I(2).4(H2O) (3), triclinic, P1, a = 10.1566(5) A, b = 10.4513(5) A, c = 10.7549(6) A, alpha = 117.552(1) degrees, beta = 96.443(1) degrees, gamma = 96.617(1) degrees, Z = 1.