Publications by authors named "Rosa Llusar"

A new method for the generation of benzyl radicals from terminal aromatic alkynes has been developed, which allows the direct cross coupling with acrylate derivatives. Our additive-free protocol employs air-stable diamino MoS cubane-type cluster catalysts in the presence of hydrogen. A sulfur-centered cluster catalysis mechanism for benzyl radical formation is proposed based on catalytic and stoichiometric experiments.

View Article and Find Full Text PDF

Semihydrogenation of internal alkynes catalyzed by the air-stable imidazolyl amino [MoSCl(ImNH)] cluster selectively affords the ()-alkene under soft conditions in excellent yields. Experimental results suggest a sulfur-based mechanism with the formation of a dithiolene adduct through interaction of the alkyne with the bridging sulfur atoms. However, computational studies indicate that this mechanism is unable to explain the experimental outcome: mild reaction conditions, excellent selectivity toward the ()-isomer, and complete deuteration of the vinylic positions in the presence of CDOD and CHOD.

View Article and Find Full Text PDF

Here, we present the synthesis of a highly efficient V-doped α-AgWO catalyst for the oxidation of sulfides to sulfones, exhibiting a high degree of tolerance towards various sensitive functional groups. Remarkably, the catalysts with 0.01% V-doping content exhibited outstanding selectivity towards the oxidation process.

View Article and Find Full Text PDF
Article Synopsis
  • Formic acid dehydrogenation is a promising method for hydrogen production, and research is focusing on more sustainable catalysts using non-noble metals.
  • A new molybdenum hydride cluster catalyst shows higher activity and selectivity than previously studied molybdenum compounds, functioning without additional additives or bases.
  • Kinetic analysis and reaction mechanisms reveal that the reaction occurs in a single step at lower temperatures, while conditions above 60 °C facilitate the full release of hydrogen and carbon monoxide, maintaining the integrity of the catalyst throughout the process.
View Article and Find Full Text PDF

In this work, α-AgCuWO (0 ≤ ≤ 0.16) solid solutions with enhanced antibacterial (against methicillin-resistant ) and antifungal (against ) activities are reported. A plethora of techniques (X-ray diffraction with Rietveld refinements, inductively coupled plasma atomic emission spectrometry, micro-Raman spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, field emission scanning electron microscopy, ultraviolet-visible spectroscopy, photoluminescence emissions, and X-ray photoelectron spectroscopy) were employed to characterize the as-synthetized samples and determine the local coordination geometry of Cu cations at the orthorhombic lattice.

View Article and Find Full Text PDF

Cubane-type MoS cluster hydrides decorated with phosphine ligands are active catalysts for the transfer hydrogenation of nitroarenes to aniline derivatives in the presence of formic acid (HCOOH) and triethylamine (EtN). The process is highly selective and most of the cluster species involved in the catalytic cycle have been identified through reaction monitoring. Formation of a dihydrogen cluster intermediate has also been postulated based on previous kinetic and theoretical studies.

View Article and Find Full Text PDF

Herein, we report a straightforward protocol for the preparation of N,N-dimethylated amines from readily available nitro starting materials using formic acid as a renewable C source and silanes as reducing agents. This tandem process is efficiently accomplished in the presence of a cubane-type Mo PtS catalyst. For the preparation of the novel [Mo Pt(PPh )S Cl (dmen) ] (3 ) (dmen: N,N'-dimethylethylenediamine) compound we have followed a [3+1] building block strategy starting from the trinuclear [Mo S Cl (dmen) ] (1 ) and Pt(PPh ) (2) complexes.

View Article and Find Full Text PDF

Treatment of the triangular [MoSCl(dbbpy)]Cl cluster ([1]Cl) with CuCl produces a novel tetrametallic cuboidal cluster [Mo(CuCl)SCl(dbbpy)][CuCl] ([2][CuCl]), 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 MM'S 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.

View Article and Find Full Text PDF

A diastereoselective synthesis of proline containing aminophosphino cubane-type Mo3S4 clusters, (P)-[Mo3S4Cl3((1S,2R)-PPro)3]Cl (Cl) and (P)-[Mo3S4Cl3((1S,2S)-PPro)3]Cl (Cl), has been achieved in high yields by reacting the corresponding enantiomerically pure PPro ((R)- and (S)-2-[(diphenylphosphino)methyl]pyrrolidine) ligands with the Mo3S4Cl4(PPh3)3(H2O)2 complex. Circular dichroism, nuclear magnetic resonance and X-ray techniques confirm that the Cl and Cl cluster cations are diastereoisomers which combine three sources of stereogenicity provided by the cluster framework, one carbon atom of the aminophosphine ligand and the nitrogen stereogenic center. The higher stability of the (+) cation is due to stabilizing vicinal ClHN interactions as well as due to the cis-fused conformation of the bicyclic system formed upon coordination of the aminophosphine ligand.

View Article and Find Full Text PDF

Substitution of the halide ligands in (Bu4N)2[Mo3S7X6] (X = Cl, Br) by diimine ligands, such as 4,4'-dimethyl-2,2'-bipyridine (dmbpy), 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), affords the neutral heteroleptic clusters Mo3S7Cl4(dmbpy) (), Mo3S7Br4(dmbpy) (), Mo3S7Br4(bpy) (), and Mo3S7Br4(phen) (). Further substitution of the halide ligands in Mo3S7Br4(diimine) clusters by dmit (1,3-dithiole-2-thione-4,5-dithiolate) allows the preparation of the mixed diimine-dithiolene neutral cluster complexes Mo3S7(dnbpy)(dmit)2 (, dnbpy = 4,4'-dinonyl-2,2'-bipyridine), Mo3S7(dcmbpy)(dmit)2 (, dcmbpy = 4,4'-dimethoxycarbonyl-2,2'-bipyridine), and Mo3S7(dcbpy)(dmit)2 (, dcbpy = 2,2'-bipyridine-4,4'-dicarboxylic acid). The optical limiting properties of complexes have been assessed by the open-aperture Z-scan technique at 570 nm, employing a nanosecond optical parametric oscillator.

View Article and Find Full Text PDF

The aminophosphine ligand (2-aminoethyl)diphenylphosphine (edpp) has been coordinated to the W3(μ-S)(μ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3](+) (1(+)) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3](+) clusters (X = F(-), Cl(-), NCS(-); 2(+)-4(+)) have been isolated by treating 1(+) with the corresponding halide or pseudohalide salt. The structure of complexes 1(+) to 4(+) contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs.

View Article and Find Full Text PDF

Two new hybrid molybdenum(IV) Mo3 S7 cluster complexes derivatized with diimino ligands have been prepared by replacement of the two bromine atoms of [Mo3 S7 Br6 ](2-) by a substituted bipyridine ligand to afford heteroleptic molybdenum(IV) Mo3 S7 Br4 (diimino) complexes. Adsorption of the Mo3 S7 cores from sample solutions on TiO2 was only achieved from the diimino functionalized clusters. The adsorbed Mo3 S7 units were reduced on the TiO2 surface to generate an electrocatalyst that reduces the overpotential for the H2 evolution reaction by approximately 0.

View Article and Find Full Text PDF

Reaction of Fe3(CO)12 with 1,2-dithiolene HSC6H2Cl2SH affords a mixture of complexes [Fe2(CO)6(μ-SC6H2Cl2S)] 1, [Fe2(SC6H2Cl2S)4] 2 and [Fe3(CO)7(μ3-SC6H2Cl2S)2] 3. In the course of the reaction the trimetallic cluster 3 is first formed and then converted into the known dinuclear compound 1 to afford finally the neutral diiron tetrakis(dithiolato) derivative 2. Compounds 2 and 3 have been studied by Mössbauer spectroscopy, X-ray crystallography and theoretical calculations.

View Article and Find Full Text PDF

Water-soluble [M3S4X3(dhbupe)3](+) diphosphino complexes (dhbupe = 1,2-bis(bis(hydroxybutyl)phosphino)ethane), 1(+) (M = Mo, X = Cl) and 2(+) (M = W; X = Br), have been synthesized by extending the procedure used for the preparation of their hydroxypropyl analogues by reaction of the M3S4(PPh3)3X4(solvent)x molecular clusters with the corresponding 1,2-bis(bishydroxyalkyl)diphosphine. The solid state structure of the [M3S4X3(dhbupe)3](+) cation possesses a C3 symmetry with a cuboidal M3S4 unit, and the outer positions are occupied by one halogen and two phosphorus atoms of the diphosphine ligand. At a basic pH, the halide ligands are substituted by hydroxo groups to afford the corresponding [Mo3S4(OH)3(dhbupe)3](+) (1OH(+)) and [W3S4(OH)3(dhbupe)3](+) (2OH(+)) complexes.

View Article and Find Full Text PDF

Bifunctional dithiolene ligands have been coordinated to the Mo(V)(O)(μ-S2)Mo(V)(O) unit to afford [Mo2O2(μ-S)2(BPyDTS2)2](2-) (1(2-)) (BPyDTS2 (2-bis-(2-pyridyl)methylene-1,3-dithiolene) dianions. Reaction of the 1(2-) molybdenum dimer with pentacarbonylchlorothenium(i) affords a tetrametallic complex of formula [Mo2O2(μ-S)2(BPyDTS2)2{Re(CO)3Cl}2](2-) (2(2-)). The monomeric (CH3)2Sn(BPyDTS2) (3) tin complex has also been prepared for comparative purposes.

View Article and Find Full Text PDF

A general protocol to access Mo(3)FeS(4)(4+) clusters selectively modified at the Fe coordination site is presented starting from the all-chlorine Mo(3)(FeCl)S(4)(dmpe)(3)Cl(3) (1) [dmpe = 1,2-bis(dimethylphosphane-ethane)] cluster and tetrabutylammonium salts (n-Bu(4)NX) (X = CN(-), N(3)(-), and PhS(-)). Clusters Mo(3)(FeX)S(4)(dmpe)(3)Cl(3) [X = CN(-) (2), N(3)(-) (3), and PhS(-) (4)] are prepared in high yield, and comparison of geometric and redox features upon modification of the coordination environment at the Fe site at parity of ligands at the Mo sites is also presented. The existence of the cubane-type Mo(3)FeS(4)(4+,5+) redox couple is demonstrated by cyclic voltammetry and for compound 1 by cluster synthesis and X-ray structure determinations.

View Article and Find Full Text PDF

The electron precise incomplete cuboidal complex [Mo(3)S(4)(dppe)(3)Br(3)]Br (1a) with 6 cluster skeletal electrons (CSE) and its halogen-mixed analogue [Mo(3)S(4)(dppe)(3)(Br,Cl)(3)](Br,Cl) (1b) can be smoothly reduced to the paramagnetic [Mo(3)S(4)(dppe)(3)X(3)] clusters (2a, X = Br; 2b, X = Cl/Br) with 7 CSE by treatment with liquid Ga.

View Article and Find Full Text PDF

Chemoselective cubes: Cubane-type [Mo(3)S(4)X(3)(dmpe)(3)](+) clusters (dmpe = 1,2-(bis)dimethylphosphinoethane), in combination with an azeotropic 5:2 mixture of HCOOH and NEt(3) as the reducing agent, act as selective cluster catalysts (X = H) or precatalysts (X = Cl) for the transfer hydrogenation of functionalized nitroarenes, without the formation of hazardous hydroxylamines.

View Article and Find Full Text PDF

The [Mo(3)S(4)Cl(3)(dhprpe)(3)](+) (1(+)) cluster cation has been prepared by reaction between Mo(3)S(4)Cl(4)(PPh(3))(3) (solvent)(2) and the water-soluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1](2)[Mo(6)Cl(14)] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand.

View Article and Find Full Text PDF

A Re(IV) cluster complex [Re(3)(μ(3)-S)(μ-S)(3)(dppe)(3)Br(3)](+) with nine cluster skeletal electrons (CSE) and a quadruplet ground state has been prepared by treatment of [Re(3)S(7)Br(6)]Br with 1,2-bis(diphenylphosphino)ethane (dppe) in MeCN.

View Article and Find Full Text PDF

The first well-defined iron-based catalyst system for the reduction of nitroarenes to anilines has been developed applying formic acid as reducing agent. A broad range of substrates including other reducible functional groups were converted to the corresponding anilines in good to excellent yields at mild conditions. Notably, the process constitutes a rare example of base-free transfer hydrogenations.

View Article and Find Full Text PDF

The electron precise [Mo(3)(μ(3)-S)(μ-S)(3)(dppe)(3)Br(3)](+) incomplete cuboidal complex with six cluster skeletal electrons (CSE) can be converted to the paramagnetic bicapped [Mo(3)(μ(3)-S)(2)(μ-S)(3)(dppe)(3)](+) cluster with an unusual seven metal electron population by treatment with (t)BuSNa, which simultaneously serves as a reducing agent and a source of the additional capping sulfur atom.

View Article and Find Full Text PDF

The gas phase fragmentation reactions of sulfur-rich [Mo(3)S(7)Br(6)](2-) (1(2-)), [Mo(3)S(7)(bdt)(3)](2-) (2(2-)), and [Mo(3)S(4)(bdt)(3)](2-) (3(2-)) (bdt = benzenedithiolate) complexes have been investigated by electrospray ionization (ESI) tandem mass spectrometry and theoretical calculations at the density functional theory level. Upon collision induced dissociation (CID) conditions, the brominated 1(2-) dianion dissociates through two sequential steps that involves a heterolytic Mo-Br cleavage to give [Mo(3)S(7)Br(5)](-) plus Br(-) followed by a two-electron redox process that affords [Mo(3)S(5)Br(5)](-) and diatomic S(2) sulfur. Dianion [Mo(3)S(7)(bdt)(3)](2-) (2(2-)) dissociates through two sequential redox processes evolving diatomic S(2) sulfur and neutral bdt to yield [Mo(3)S(5)(bdt)(3)](2-) and [Mo(3)S(5)(bdt)(2)](2-), respectively.

View Article and Find Full Text PDF

The molybdenum(IV) cluster hydrides of formula [Mo(3)S(4)H(3)(diphosphine)(3)](+) with diphosphine = 1,2-(bis)dimethylphosphinoethane (dmpe) or (+)-1,2-bis-(2R,5R)-2,5-(dimethylphospholan-1-yl)ethane ((R,R)-Me-BPE) have been isolated in moderate to high yields by reacting their halide precursors with borohydride. Complex [Mo(3)S(4)H(3)((R,R)-Me-BPE)(3)](+) as well as its tungsten analogue are obtained in optically pure forms. Reaction of the incomplete cuboidal [M(3)S(4)H(3)((R,R)-Me-BPE)(3)](+) (M = Mo, W) complex with acids in CH(2)Cl(2) solution shows kinetic features similar to those observed for the related incomplete cuboidal [W(3)S(4)H(3)(dmpe)(3)](+) cluster.

View Article and Find Full Text PDF

The synthesis, crystal structure and solution characterization of the cubane-type [Mo(3)(FeCl)S(4)(dmpe)(3)Cl(3)] (1) (dmpe = 1,2-bis(dimethylphophane-ethane)) cluster are reported and the ligand substitution processes of chloride by thiophenolate investigated. The kinetics and the intimate mechanism of these substitutions reveal that compound 1 undergoes a number of Fe and Mo site specific ligand substitution reactions in acetonitrile solutions. In particular, PhS(-) coordination at the tetrahedral Fe site proceeds in a single resolved kinetic step whereas such substitutions at the Mo sites proceed more slowly.

View Article and Find Full Text PDF