Search results for "Cluster chemistry"
showing 9 items of 9 documents
Synthesis, reactivity and structures of ruthenium carbonyl clusters with telluride and hydride ligands
2002
The reaction of [Cp* 2 Nb(Te 2 H)] ( 1 ) (Cp*=C 5 Me 5 ) with [Ru 3 (CO) 12 ] in boiling toluene gave [Ru 3 (μ 2 -H) 2 (CO) 9 (μ 3 -Te)] ( 2 ), [Ru 6 (μ 3 -H)(CO) 15 (μ 3 -Te) 3 ][Cp* 2 Nb(CO) 2 ] ( 3 ) and [Ru 5 (μ 2 -H)(CO) 14 (μ 4 -Te)][Cp* 2 Nb(CO) 2 ] ( 4 ) along with already known [Ru 4 (CO) 11 (μ 4 -Te) 2 ] ( 5 ). Complexes 2 – 4 were analytically and spectroscopically characterized and X-ray diffraction analyses of 3 and 4 were carried out. The anion of 3 is built up of a triangular hexametallic core of C 3 v symmetry, in which the central Ru 3 triangle, being bridged by a μ 3 -H ligand, is composed of three corner-linked Ru 3 Te tetrahedra. The main structural feature of the anion …
Real-Time Observation of “Soft” Magic-Size Clusters during Hydrolysis of the Model Metallodrug Bismuth Disalicylate
2021
International audience; Colloidal bismuth therapeutics have been used for hundreds of years, yet remain mysterious. Here we report an X-ray pair distribution function (PDF) study of the solvolysis of bismuth disalicylate, a model for the metallodrug bismuth subsalicylate (Pepto-Bismol). This reveals catalysis by traces of water, followed by multistep cluster growth. The ratio of the two major species, {Bi9O7} and {Bi38O44}, depends on exposure to air, time, and the solvent. The solution-phase cluster structures are of significantly higher symmetry in comparison to solid-state analogues, with reduced off-center Bi3+ displacements. This explains why such “magic-size” clusters can be both stab…
New structural motifs in Mn cluster chemistry from the ketone/gem-diol and bis(gem-diol) forms of 2,6-di-(2-pyridylcarbonyl)pyridine: {MnII4MnIII2} a…
2016
The employment of the tripyridyl/diketone ligand 2,6-di-(2-pyridylcarbonyl)pyridine [(py)CO(py)CO(py)], in conjunction with azides (N3−), in Mn cluster chemistry has afforded the mixed-valence (II/III) complexes [MnII4MnIII2(N3)6Cl4(L1)2(DMF)4] (1) and [MnII4MnIII6O2(N3)12(L1)2(L2H)2(DMF)6] (2) in good yields. The resulting ligands L12− and L2H3− are the dianion and trianion of the ketone/gem-diol (L1H2) and bis(gem-diol) (L2H4) forms of (py)CO(py)CO(py), respectively, as derived from the metal-assisted hydrolysis of the parent dicarbonyl organic compound. Under the same synthetic conditions (i.e., reaction solvents, temperature and stirring time), the chemical identity of the two complexes…
Improved Photocatalytic Activity of Polysiloxane TiO2 Composites by Thermally Induced Nanoparticle Bulk Clustering and Dye Adsorption
2021
Fine control of nanoparticle clustering within polymeric matrices can be tuned to enhance the physicochemical properties of the resulting composites, which are governed by the interplay of nanoparticle surface segregation and bulk clustering. To this aim, out-of-equilibrium strategies can be leveraged to program the multiscale organization of such systems. Here, we present experimental results indicating that bulk assembly of highly photoactive clusters of titanium dioxide nanoparticles within an in situ synthesized polysiloxane matrix can be thermally tuned. Remarkably, the controlled nanoparticle clustering results in improved degradation photocatalytic performances of the material under …
Carbonyl Transition Metal Complexes of a Silaborate Ligand
1998
Reaction between three equivalents of the silaborate [NEt4][MeSiB10H12] (2) and one equivalent of [Ru3(CO)12] resulted in almost quantitative formation of the mononuclear transition metal complex [NEt4][Ru(CO)3(η5-MeSiB10H10)] (5), which was characterized by X-ray structure analysis. The trinuclear ruthenium complex [NEt4][Ru3(CO)8(η5-MeSiB10H10)] (7) was synthesized in high yield from the reaction of one equivalent of 2 and [Ru3(CO)12]. The cluster 7 reacts with two equivalents of PMe2Ph with substitution of two carbonyl groups to give the substitution product [NEt4][Ru3(CO)6(PMe2Ph)2(η5-MeSiB10H10)] (8).
A theoretical analysis of the structure and properties of B26H30 isomers. Consequences to the laser and semiconductor doping capabilities of large bo…
2019
Decaborane(14), nido-B10H14, is the major commercially available molecular building block in boron cluster chemistry. The condensation of two such {nido-B10} blocks gives the known isomers of B18H22 – a molecule used in the fabrication of p-type semiconductors and capable of blue laser emission. Here, we computationally determine the structures and thermodynamic stabilities of 20 possible B26H30 regioisomers constructed from the fusion of three {nido-B10} blocks with the three subclusters conjoined by two-boron atom shared edges. In addition, density functional theory, time-dependent (TD)-DFT and multiconfigurational CASPT2 methods have been used to model and investigate the physical and ph…
[{(C5Me5)2Nb}2PdTe4], a heterometallic palladium telluride cluster with a planar PdTe4 fragment
2007
Abstract The reaction of [ Cp 2 ∗ Nb ( Te 2 H ) ] (Cp∗ = η5-C5Me5) with [Pd(DBA)2] (DBA = dibenzylidenacetone) and dppm (bis(diphenylphosphanyl)methane) gave the new tetratelluropalladate cluster [ ( Cp 2 ∗ Nb ) 2 PdTe 4 ] (1), which has been characterised by means of elemental analysis, FD-MS and X-ray crystallography. The structure of compound 1 contains a planar PdTe4 rectangle to which two niobocene groups are coordinated. DFT calculations on the hypothetical [PdTe4]2− anion and comparison of the results with those of the W and Ni homologues show that the planar arrangement of Te ligands in 1 is due to the intrinsic property of the central Pd atom.
Local Structure of Supported Keggin and Wells-Dawson Heteropolyacids and Its Influence on the Catalytic Activity
2019
[EN] Keggin [PW12O40]3– and Wells–Dawson [P2W18O62]6– heteropolyanions are nanosized transition-metal-oxygen clusters belonging to the heteropolyacids (HPAs) family. They are widely used as catalysts due to their high Brønsted acidity, and their dispersion on solid supports favors the accessibility to their acid sites generally increasing the catalytic activity. A series of binary materials composed of Keggin or Wells–Dawson HPAs and SiO2, TiO2, and ZrO2 have been prepared by impregnation or solvothermal methods. Remarkable differences have been found in the catalytic activities among the unsupported and supported HPAs. These differences have been correlated in the past to the structural ch…
Reactions with a Metalloid Tin Cluster {Sn10[Si(SiMe3)3]4}(2-): Ligand Elimination versus Coordination Chemistry.
2015
Chemistry that uses metalloid tin clusters as a start- ing material is of fundamental interest towards understand- ing the reactivity of such compounds. Since we identified {Sn10(Si(SiMe3)3)4} 2� 7 as an ideal candidate for such reactions, we present a further step in the understanding of metalloid tin cluster chemistry. In contrast to germanium chemistry, ligand elimination seems to be a major reaction channel, which leads to the more open metalloid cluster {Sn10(Si(SiMe3)3)3} � 9, in which the Sn core is only shielded by three Si(SiMe3)3 ligands. Compound 9 is obtained through different routes and is crystallised together with two differ- ent countercations. Besides the structural charact…