Hydrolysis of Element (White) Phosphorus under the Action of Heterometallic Cubane-Type Cluster {Mo3PdS4}

Reaction of heterometallic cubane-type cluster complexes—[Mo₃{Pd(dba)}S₄Cl₃(dbbpy)₃]PF₆, [Mo₃{Pd(tu)}S₄Cl₃(dbbpy)₃]Cl and [Mo₃{Pd(dba)}S₄(acac)₃(py)₃]PF₆, where dba—dibenzylideneacetone, dbbpy—4,4′-di-tert-butyl-2,2′-bipyridine, tu—thiourea, acac—acetylacetonate, py—pyridine, with white phosphorus (P₄) in the presence of water leads to the formation of phosphorous acid H₃PO₃ as the major product. The crucial role of the Pd atom in the cluster core {Mo₃PdS₄} has been established in the hydrolytic activation of P₄ molecule. The main intermediate of the process, the cluster complex [Mo₃{PdP(OH)₃}S₄Cl₃(dbbpy)₃]⁺ with coordinated P(OH)₃ molecule and phosphine PH₃, have been detected by ³¹P NMR spectroscopy in the reaction mixture.

Interaction of Hydrophobic Tungsten Cluster Complexes with a Phospholipid Bilayer

Nanoconstructions composed of lipid vesicles and inorganic units (nanoparticles, metal complexes) arouse much interest across materials science and nanotechnology as hybrid materials combining useful functionalities from both parts. Ideally, these units are to be embedded into the bilayer to keep the biophysical performance of lipid vesicles having inorganic moieties screened from the environment. This can be achieved by doping a lipid bilayer with cluster complexes of transition metals. In this work, we report the preparation of nanoparticles from trinuclear W₃S₄ cluster complexes and egg phosphatidylcholine. A systematic study of their properties was performed by the differential scanning calorimetry, NMR spectroscopy, dynamic light scattering, and transmission electron microscopy. Phospholipids and clusters have been found to spontaneously self-assemble into novel cluster-lipid hybrid materials. The behavior of clusters in the hydrophobic lipid environment is determined by the structure of the ligands and cluster-to-lipid ratio. Intact cluster complexes bearing compact hydrophobic ligands are embedded into the hydrophobic midplane of a lipid bilayer, whereas cluster complexes bearing larger ligands drive the aggregation of lipids and cluster complexes. Considering these differences, it could be possible to obtain different self-assembled associates such as cluster-doped liposomes or lipid-covered crystals. These cluster-lipid hybrids can be a platform for the design of new materials for nanotechnology.

Investigation of electronic structure of tri- and tetranuclear molybdenum clusters by X-ray photoelectron and emission spectroscopies and quantum chemical methods

Charge state studies of compounds [Mo₃S₄(tu)₈(H₂O)]Cl₄·4H₂O (1), [Mo₃S₄Cl₃(dbbpy)₃]Cl·5H₂O (2), [Mo₃S₄(CuCl)Cl₃(dbbpy)₃][CuCl₂] (3), containing {Mo₃S₄}⁴⁺ and {Mo₃CuS₄}⁵⁺ cluster cores bearing terminal thiourea (tu) or 4,4'-di-tert-butyl-2,2'-bipyridine (dbbpy) ligands, have been performed by X-ray photoelectron and X-ray emission spectroscopies combined with quantum chemical calculations. The best agreement between theory and experiments has been obtained using the B3LYP method. According to the experimental and calculated data, the Mo atoms are in the oxidation state 4+ for all compounds. The energies and shapes of the Cu2p lines indicate formal oxidation states of Cu as 1+. The coordination of Сu(I) to the cluster {Mo₃S₄} in 3 does not lead to significant changes in the charge state of the molybdenum atoms and the {Mo₃S₄} unit can be considered as a tridentate metallothia crown ether.

Hemilability of phosphine-thioether ligands coordinated to trinuclear Mo3S4 cluster and its effect on hydrogenation catalysis

Phosphine-thioether ligands were coordinated to the Mo₃S₄ cluster to afford [Mo₃S₄Cl₃(PS)₃]⁺ complexes. Their catalytic activity in nitrobenzene reduction reflects the different hemilabile behaviours of PS1, PS2 and PS3.

Kinetics Aspects of the Reversible Assembly of Copper in Heterometallic Mo3CuS4 Clusters with 4,4'-Di-tert-butyl-2,2'-bipyridine

Treatment of the triangular [Mo₃S₄Cl₃(dbbpy)₃]Cl cluster ([1]Cl) with CuCl produces a novel tetrametallic cuboidal cluster [Mo₃(CuCl)S₄Cl₃(dbbpy)₃][CuCl₂] ([2][CuCl₂]), whose crystal structure was determined by X-ray diffraction (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine). This species, which contains two distinct types of Cu(I), is the first example of a diimine-functionalized heterometallic M₃M'S₄ cluster. Kinetics studies on both the formation of the cubane from the parent trinuclear cluster and its dissociation after treatment with halides, supported by NMR, electrospray ionization mass spectrometry, cyclic voltammetry, and density functional theory calculations, are provided. On the one hand, the results indicate that addition of Cu(I) to [1]⁺ is so fast that its kinetics can be monitored only by cryo-stopped flow at -85 °C. On the other hand, the release of the CuCl unit in [2]⁺ is also a fast process, which is unexpectedly assisted by the CuCl₂^- counteranion in a process triggered by halide (X^-) anions. The whole set of results provide a detailed picture of the assembly-disassembly processes in this kind of cluster. Interconversion between trinuclear M₃S₄ clusters and their heterometallic M₃M'S₄ derivatives can be a fast process occurring readily under the conditions employed during reactivity and catalytic studies, so their occurrence is a possibility that must be taken into account in future studies.