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Theocharis C Stamatatos - One of the best experts on this subject based on the ideXlab platform.
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Oximato-Based Ligands in 3d/4f‑Metal Cluster Chemistry: A Family of {Cu3Ln} Complexes with a “Propeller”-like Topology and Single-Molecule Magnetic Behavior
2018Co-Authors: Anne Worrell, Albert Escuer, Di Sun, Julia Mayans, Christos Lampropoulos, Theocharis C StamatatosAbstract:The organic chelating and bridging ligands 9,10-phenanthrenedione-9-oxime (phenoxH) and 9,10-phenanthrenedione-9,10-dioxime (phendoxH2) were synthesized and subsequently employed for the first time in heteroMetallic 3d/4f-Metal Cluster chemistry. The general reaction between CuCl2·2H2O, LnCl3·6H2O, phenoxH, and NEt3 in a 1:2:2:4 molar ratio, in a solvent mixture comprising MeCN and MeOH, afforded brown crystals of a new family of [Cu3LnCl3(phenox)6(MeOH)3] Clusters (Ln = Gd (1), Tb (2), Dy (3)) that possess an unprecedented [Cu3Ln(μ-NO)6]3+ “propeller”-like core. Complexes 1–3 are the first {Cu3Ln} Clusters in which the outer CuII and the central LnIII atoms are solely bridged by diatomic oximato bridges. The {Cu-N-O-Ln} bridging units are very distorted with torsion angles spanning the range 35.5–48.9° and 25.2–55.6° in 1 and 2, respectively. As a result, complexes 1–3 are antiferromagnetically coupled, in agreement with previously reported magnetostructural criteria for oximato-bridged Cu/Ln complexes. The magnetic susceptibility data for all complexes were nicely fit to an isotropic spin Hamiltonian (for 1) or a Hamiltonian that accounts for the spin of the CuII atoms, the spin component of the LnIII, the spin–orbit coupling (λ), an axial ligand-field component around the LnIII atoms (Δ), and the Zeeman effect (for the anisotropic 2 and 3). The resulting fit parameters were J = −1.34 cm–1 and g = 2.10 (1), J = −1.42 cm–1, gCu = 2.10, and Δ = −26.3 cm–1 (2), and J = −1.70 cm–1, gCu = 2.05, and Δ = −38.1 cm–1 (3). The reported fitting procedure, implemented in the PHI program, is here used for the first time. Even if this method is only valid in high-symmetry Ln environments, when it is properly used allows a very simple and efficient method to obtain the exchange parameters. In light of the negative anisotropy, compounds 2 and 3 were found to exhibit frequency-dependent tails of out-of-phase signals in the presence of a small external dc field, characteristic of the slow magnetization relaxation of a single-molecule magnet. By using the Kramers–Kronig equations, the effective energy barriers (Ueff) were derived and reported as Ueff = 10.1 and 5.4 cm–1 for 2 and 3, respectively
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dodecanuclear 3d 4f Metal Clusters with a star of david topology single molecule magnetism and magnetocaloric properties
Chemical Communications, 2016Co-Authors: Dimitris Alexandropoulos, Luis Cunhasilva, Giulia Lorusso, Marco Evangelisti, Jinkui Tang, Theocharis C StamatatosAbstract:A family of interwoven molecular inorganic knots, shaped like the ‘Star of David’, was prepared by the employment of naphthalene-2,3-diol in 3d/4f-Metal Cluster chemistry; the isoskeletal dodecanuclear compounds exhibit slow relaxation of the magnetization and magnetocaloric properties, depending on the Metal ion.
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initial employment of α benzoin oxime as a route to high nuclearity Metal Clusters decanuclear cuii complexes with a wheel topology
Dalton Transactions, 2009Co-Authors: Gina Vlahopoulou, Theocharis C Stamatatos, Vassilis Psycharis, Spyros P Perlepes, George ChristouAbstract:The initial employment of α-benzoin oxime (bzoxH2) in Metal Cluster chemistry has provided access to a new family of decanuclear CuII complexes with a loop or single-strand wheel topology; the CuII10Clusters are antiferromagnetically-coupled with an S = 0 spin ground state, as expected for even-membered loop arrays of CuII atoms.
Ferran Feixas - One of the best experts on this subject based on the ideXlab platform.
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Metal Cluster electrides a new type of molecular electride with delocalised polyattractor character
Chemistry: A European Journal, 2018Co-Authors: Ouissam El Bakouri, Veronica Postils, Marc Garciaborras, Simone Calvello, Alessandro Soncini, Eduard Matito, Josep M. Luis, Miquel Duran, Ferran FeixasAbstract:: Electrides are ionic substances containing isolated electrons. These confined electrons are topologically characterised by a quasi-atom, that is, a non-nuclear attractor (NNA) of the electron density. The electronic structure of the octahedral 4 A1g Li6+ and 5 A1g Be6 species shows that these species have a large number of NNAs. These NNAs have highly delocalised electron densities and, as a result, the chemical bonding pattern of these systems is reminiscent of that in solid Metals, in which Metal cations are surrounded by a "sea" of delocalised valence electrons. We propose the term Metal Cluster electrides to refer to this new class of compounds. In this study, we establish a computational protocol to identify, characterize, and design Metal Cluster electrides and we elucidate the intricate bonding patterns of this particular type of species.
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Metal Cluster electrides a new type of molecular electride with delocalised polyattractor character
Chemistry: A European Journal, 2018Co-Authors: Ouissam El Bakouri, Veronica Postils, Marc Garciaborras, Simone Calvello, Alessandro Soncini, Eduard Matito, Josep M. Luis, Miquel Duran, Ferran FeixasAbstract:: Electrides are ionic substances containing isolated electrons. These confined electrons are topologically characterised by a quasi-atom, that is, a non-nuclear attractor (NNA) of the electron density. The electronic structure of the octahedral 4 A1g Li6+ and 5 A1g Be6 species shows that these species have a large number of NNAs. These NNAs have highly delocalised electron densities and, as a result, the chemical bonding pattern of these systems is reminiscent of that in solid Metals, in which Metal cations are surrounded by a "sea" of delocalised valence electrons. We propose the term Metal Cluster electrides to refer to this new class of compounds. In this study, we establish a computational protocol to identify, characterize, and design Metal Cluster electrides and we elucidate the intricate bonding patterns of this particular type of species.
Eduard Matito - One of the best experts on this subject based on the ideXlab platform.
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Metal Cluster electrides a new type of molecular electride with delocalised polyattractor character
Chemistry: A European Journal, 2018Co-Authors: Ouissam El Bakouri, Veronica Postils, Marc Garciaborras, Simone Calvello, Alessandro Soncini, Eduard Matito, Josep M. Luis, Miquel Duran, Ferran FeixasAbstract:: Electrides are ionic substances containing isolated electrons. These confined electrons are topologically characterised by a quasi-atom, that is, a non-nuclear attractor (NNA) of the electron density. The electronic structure of the octahedral 4 A1g Li6+ and 5 A1g Be6 species shows that these species have a large number of NNAs. These NNAs have highly delocalised electron densities and, as a result, the chemical bonding pattern of these systems is reminiscent of that in solid Metals, in which Metal cations are surrounded by a "sea" of delocalised valence electrons. We propose the term Metal Cluster electrides to refer to this new class of compounds. In this study, we establish a computational protocol to identify, characterize, and design Metal Cluster electrides and we elucidate the intricate bonding patterns of this particular type of species.
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Metal Cluster electrides a new type of molecular electride with delocalised polyattractor character
Chemistry: A European Journal, 2018Co-Authors: Ouissam El Bakouri, Veronica Postils, Marc Garciaborras, Simone Calvello, Alessandro Soncini, Eduard Matito, Josep M. Luis, Miquel Duran, Ferran FeixasAbstract:: Electrides are ionic substances containing isolated electrons. These confined electrons are topologically characterised by a quasi-atom, that is, a non-nuclear attractor (NNA) of the electron density. The electronic structure of the octahedral 4 A1g Li6+ and 5 A1g Be6 species shows that these species have a large number of NNAs. These NNAs have highly delocalised electron densities and, as a result, the chemical bonding pattern of these systems is reminiscent of that in solid Metals, in which Metal cations are surrounded by a "sea" of delocalised valence electrons. We propose the term Metal Cluster electrides to refer to this new class of compounds. In this study, we establish a computational protocol to identify, characterize, and design Metal Cluster electrides and we elucidate the intricate bonding patterns of this particular type of species.
Yanggang Wang - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous single Cluster catalysts for selective semihydrogenation of acetylene with graphdiyne supported triatomic Clusters
Journal of Physical Chemistry C, 2019Co-Authors: Denghui Xing, Yanggang WangAbstract:Graphdiyne (GDY) is a newly discovered, novel carbon material, highly promising for chemical, physical, material, and industrial applications. The unique yet natural pores of GDY provide a novel prospect to design stable Metal-Cluster catalysts strongly bonded to its carbon framework. We report here a theoretical study using density functional theory on a heterogeneous-surface single-Cluster catalyst (SCC) supported by GDY. This SCC features a triatomic Metal Cluster strongly anchored on the 18-member ring hexagon of the GDY support, MxM′3–x/GDY (M, M′ = Ru, Os), and can hydrogenate acetylene to ethylene with significant selectivity. This feature is attributed to a synergistic effect among the Metal atoms in the Cluster and the role of GDY as a charge buffer. State-of-the-art chemical bonding and microkinetic analyses are performed to understand the mechanism and catalytic performance. Our work highlights the importance of stably anchored surface-isolated Metal Clusters in heterogeneous catalysis and the ...
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heterogeneous single Cluster catalysts for selective semihydrogenation of acetylene with graphdiyne supported triatomic Clusters
The Journal of Physical Chemistry, 2019Co-Authors: Denghui Xing, Yanggang WangAbstract:Graphdiyne (GDY) is a newly discovered, novel carbon material, highly promising for chemical, physical, material, and industrial applications. The unique yet natural pores of GDY provide a novel prospect to design stable Metal-Cluster catalysts strongly bonded to its carbon framework. We report here a theoretical study using density functional theory on a heterogeneous-surface single-Cluster catalyst (SCC) supported by GDY. This SCC features a triatomic Metal Cluster strongly anchored on the 18-member ring hexagon of the GDY support, MₓM′₃–ₓ/GDY (M, M′ = Ru, Os), and can hydrogenate acetylene to ethylene with significant selectivity. This feature is attributed to a synergistic effect among the Metal atoms in the Cluster and the role of GDY as a charge buffer. State-of-the-art chemical bonding and microkinetic analyses are performed to understand the mechanism and catalytic performance. Our work highlights the importance of stably anchored surface-isolated Metal Clusters in heterogeneous catalysis and the synergy among Metal atoms in a Cluster and the peripheral Metal–support interfacial atoms.
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the role of reducible oxide Metal Cluster charge transfer in catalytic processes new insights on the catalytic mechanism of co oxidation on au tio2 from ab initio molecular dynamics
Journal of the American Chemical Society, 2013Co-Authors: Yanggang Wang, Yeohoon Yoon, Vassiliki Alexandra Glezakou, Roger RousseauAbstract:To probe Metal particle/reducible oxide interactions density functional theory based ab initio molecular dynamics studies were performed on a prototypical Metal Cluster (Au20) supported on reducible oxides (rutile TiO2(110)) to implicitly account for finite temperature effects and the role of excess surface charge in the Metal oxide. It is found that the charge state of the Au particle is negative in a reducing chemical environment whereas in the presence of oxidizing species coadsorbed to the oxide surface the Cluster obtained a net positive charge. In the context of the well-known CO oxidation reaction, charge transfer facilitates the plasticization of Au20, which allows for a strong adsorbate induced surface reconstruction upon addition of CO leading to the formation of mobile Au–CO species on the surface. The charging/discharging of the Cluster during the catalytic cycle of CO oxidation enhances and controls the amount of O2 adsorbed at oxide/Cluster interface and strongly influences the energetics of...
Shingo Ichimura - One of the best experts on this subject based on the ideXlab platform.
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production of stable ion beam of os3 co 12 with compact Metal Cluster complex ion source
Japanese Journal of Applied Physics, 2006Co-Authors: Yukio Fujiwara, Toshiyuki Fujimoto, Hidehiko Nonaka, Akira Kurokawa, Kouji Kondou, Yoshikazu Teranishi, Shingo IchimuraAbstract:Metal-Cluster-complex ion beams were produced stably using a Cluster ion source, which is compact enough to be installed in commonly used secondary ion mass spectrometry (SIMS) systems. As a Metal Cluster complex, triosmium dodecacarbonyl, Os3(CO)12, was utilized, which has a molecular weight of 906.7. Since precise temperature control is necessary to sublimate the Metal Cluster complex stably without thermal decomposition, the ion source was equipped with compact heat-removal devices in addition to an external heater. Experimental results showed that the crucible temperature of the Metal Cluster complex can be maintained at about 130 °C in continuous operation, which is an appropriate temperature for sublimation without the problem of decomposition. The ion source produced steady-state beams of Os3(CO)n+ (n=7 or 8) ions with a beam current exceeding 10 nA at 10 keV. Beam current increased with gas pressure, depending on the temperature of the crucible holding the Metal Cluster complex. The rate of the change in beam current was within a few percent per hour; hence, in view of stability, the ion source was confirmed as usable in SIMS. Furthermore, beam profile was investigated using a Faraday cup with a knife-edge as well as a GaAs/AlAs multilayer substrate as a beam target.
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application of Metal Cluster complex ion beam for low damage sputtering
Surface and Interface Analysis, 2005Co-Authors: Toshiyuki Fujimoto, Takeshi Mizota, Hidehiko Nonaka, Akira Kurokawa, Shingo IchimuraAbstract:Metal Cluster complexes, including the colloidal Metal Cluster, were applied to establish the low damage sputtering method. Electro-spray-like ionization using an ink-jet nozzle has the potential to produce a Cluster ion beam. A colloidal Au Cluster of size 5 nm made a large crater-like hole at the carbon sheet. Copyright © 2005 John Wiley & Sons, Ltd.
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development of compact Cluster ion sources using Metal Cluster complexes ionization properties of Metal Cluster complexes
Applied Surface Science, 2004Co-Authors: Takeshi Mizota, Toshiyuki Fujimoto, Hidehiko Nonaka, Akira Kurokawa, Shingo IchimuraAbstract:Abstract In order to develop a new compact Cluster ion source as a low damage sputtering source for SIMS to analyze ultra-shallow dopant state we have studied the possibility of using a Metal Cluster complex as an ion beam source. Metal Cluster complexes such as Os 3 (CO) 12 and Ir 4 (CO) 12 have been studied from the view point of their stability in high vacuum and how to ionize them by using the electron ionization QMS and the XeCl laser ionization TOF. In the case of electron ionization QMS, peaks of Os 3 (CO) n + ( n =0–12) and Ir 4 (CO) n + ( n =0–12) were observed without the fragment ions such as a monomer, a dimer, etc. In the case of laser ionization TOF, peaks of the fragment and the parent ions without a carbonyl ligand were observed from Os 3 (CO) 12 , and Ir 4 (CO) 12 . The temperature dependence of fragmentation has also been discussed.