Marta S. Krawczyk

trans-Dioxidotetra-pyridine-rhenium(V) triiodide.

In the title salt, [ReO2(C5H5N)4]I3, the cation and anion are both located on centres of symmetry. The ReV atom adopts a trans-ReO2N4 octahedral coordination and short intramolecular C—H⋯O contacts occur within the cation. In the crystal, the cations form layers perpendicular to [100] and a weak C—H⋯O interaction links the cations.

First oxido-bridged cubo-octahedral hexanuclear rhenium clusters.

The first discrete hexanuclear metal clusters with cores adopting the M6(μ-O)12 cubo-octahedral topology have been synthesized in the course of a simple one-pot reaction. We present a new class of rhenium clusters which are the first hexanuclear rhenium complexes with 12 bridging ligands and the first clusters with octahedrally arranged Re atoms bridged only by O atoms forming a unique cube-like Re6(μ-O)12 unit. Our synthetic strategy demonstrates a new approach to the syntheses of polynuclear rhenium complexes under mild conditions. We discovered that the [Re6(μ-O)12(3-Mepy)6]BPh4 cluster compound has the ability to undergo reversible or/and quasireversible redox reactions without changing spatial structure and overall geometry. Subsequently, a reduction reaction of [Re6(μ-O)12(3-Mepy)6]BPh4 was performed successfully and almost quantitatively resulting in the formation of the molecular [Re6(μ-O)12(3-Mepy)6] complex.

On rhenium(I)–silver(I) cyanide porous macrocyclic clusters

The first cyanide rhenium(I)–silver(I) clusters were synthesized in the course of simple one-pot high-yielding reactions. This new class of obtained self-assembled, cyclic octanuclear complexes is composed of pseudo-square-shaped {Re4Ag4(μ-CN)8} units, which, along with PPh3 ligands, adopt an approximately block-like overall geometry. We discovered that the studied cavity-shaped clusters feature a channeling crystal network capable of hosting smaller molecules and exhibit the ability to undergo reversible guest solvent sorption. Depending on the reaction conditions, the tetranuclear complex [Re2Ag2(μ-CN)4(CO)4(PPh3)6] and the species of the formal motif {ReAg1.5(CN)2.5(CO)2(PPh3)2} can be formed.

Synthesis, structural characterization and catalytic potential of oxidovanadium(IV) and dioxidovanadium(V) complexes with thiazole-derived NNN-donor ligand

Abstract Reaction between the tridentate NNN donor ligand, (E)-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)benzo[d]thiazole (HL), and V2O5 in ethanol gave a new vanadium(V) complex, [VO2L] (1), while the similar reaction by using [VIVO(acac)2] as the metal source gave two different types of crystals related to compounds [VO2L] (1) and [VIVO(acac)L] (2). The molecular structures of the complexes were determined by single-crystal X-ray diffraction and spectroscopic characterization was carried out by means of FT-IR, UV–vis and NMR experiments as well as elemental analysis. The oxidovanadium(IV) and dioxidovanadium(V) species were used as catalyst precursors for olefin oxidation in the presence of hydrogen peroxide (H2O2) as an oxidant. Under similar experimental conditions, the presence of 1 resulted in higher oxidation conversion than 2.

Geometries of hexanuclear rhenium clusters

So far, the hexanuclear rhenium clusters have been known to adopt two kinds of geometry: one described as rhenium octahedron included in a cube built up from eight bridging μ3-ligands and the second one, where rhenium atoms are arranged in a trigonal prism bridged by two μ3and six μ-ligands (Fig. 1a,b). In the first case the core of octahedral rhenium clusters have [Re6(μ3Q)8-n(μ3-X)6+n] n-4 stoichiometry, where Q = S, Se, Te; X = Cl, Br, while the second type of geometry is observed for clusters of the formula [Re6(μBr)6(μ3-Br)2Br6] [1]. Our recent research proved that octahedral rhenium clusters can also adopt another kind of geometry, where rhenium atoms are bridged by μ-ligands only (Fig. 1c). Fig. 1. Three kinds of geometry observed in hexanuclear rhenium clusters.

2,2'-[(1E,2E)-1,2-Bis(hy-droxy-imino)-ethane-1,2-di-yl]dipyridinium hexa-chloridorhenate(IV).

The title salt, (C12H12N4O2)[ReCl6], consists of 2,2′-[(1E,2E)-1,2-bis(hydroxyimino)ethane-1,2-diyl]dipyridinium cations and [ReCl6]2− anions which are both located on inversion centres. Each cation consists of a glyoxime moiety attached to two protonated pyridine rings in ortho positions. In the crystal, E,E isomers of the cation are observed which differ in the spatial arrangement of the pyridine rings. These rings are positionally disordered over two positions with site-occupancy factors of 0.786 (7) and 0.214 (7). The geometry of the cation is compared with that of a recently reported dipyridylglyoxime with the same configuration. The cations and anions are involved in a network of intermolecular O—H⋯Cl, N—H⋯Cl and C—H⋯Cl hydrogen bonds.