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First-principles calculations of inorganic metallocene nanowires. NANOSCALE ADVANCES 2024; 6:985-989. [PMID: 38298596 PMCID: PMC10825901 DOI: 10.1039/d3na00926b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 12/29/2023] [Indexed: 02/02/2024]
Abstract
Inspired by the recently synthesized inorganic metallocene derivatives Fe(P4)22-, we have identified four stable inorganic metallocene nanowires, MP4 (M = Sc, Ti, Cr and Fe) in configurations of either regular quadrangular prism (Q-type) or anticube (A-type), and further investigated their magnetic and electronic characteristics utilizing the first-principles calculation. It shows that CrP4 is a ferromagnetic metal, while other nanowires are semiconducting antiferromagnets with bandgaps of 0.44, 1.88, and 2.29 eV within the HSE06 level. It also shows that both ScP4 and TiP4 can be stabilized in the Q-type and A-type, corresponding to the antiferromagnetic and ferromagnetic ground states, respectively, indicating a configuration-dependent magnetism. The thermodynamic and lattice stabilities are confirmed by the ab initio molecular dynamics and phonon spectra. This study has unmasked the structural and physical properties of novel inorganic metallocene nanowires, and revealed their potential application in spintronics.
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Transition Metal Triple-decker Sandwich Complexes Containing Group 13 Elements. Chem Asian J 2024; 19:e202300864. [PMID: 37943517 DOI: 10.1002/asia.202300864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/02/2023] [Accepted: 11/05/2023] [Indexed: 11/10/2023]
Abstract
Transition metal triple-decker complexes are an interesting class of sandwich complexes that engrossed great attention due to their structures and properties. Over the decades, synthesis of triple-decker complexes featuring homocyclic, heterocyclic or π-conjugated rings as middle decks have been abundantly reported. In this regard, the chemistry of such complexes bearing boron in the middle deck are well explored due to the ability of boron-containing cycles to readily coordinate bifacially with metal atoms thereby forming triple-decker complexes. On the other hand, electron counting rules and theoretical calculations have strengthened our knowledge of the structure and bonding in these complexes. Further, these complexes can be used as synthons to generate organometallic polymers having interesting electronic, optical and magnetic properties that can be appropriately tuned to cater to a wide range of applications. In our quest for novel metallaboranes and metallaheteroboranes, we have been successful in isolating various triple-decker complexes that feature boron in the middle deck. This review explained elaborately the synthesis, structures, and bonding in such complexes reported by us and others.
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Comparison of Magnetic Deflection among Neutral Sodium-Doped Clusters: Na(H 2O) n, Na(NH 3) n, Na(MeOH) n, and Na(DME) n. J Phys Chem A 2023; 127:8544-8555. [PMID: 37794760 PMCID: PMC10591511 DOI: 10.1021/acs.jpca.3c03820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/06/2023] [Indexed: 10/06/2023]
Abstract
Using a pulsed Stern-Gerlach deflection experiment, we present the results of a comparative study on the magnetic properties of neutral sodium-doped solvent clusters Na(Sol)n with n = 1-4 (Sol: H2O, NH3, CH3OH, CH3OCH3). Experimental deflection ratios are compared with values calculated from molecular dynamics simulations. NaNH3 and NaH2O are deflected as a spin 1/2 system, consistent with spin transitions occurring on a time scale significantly longer than 100 μs. For all other clusters, reduced deflection is observed. The observed magnetic deflection behavior is correlated to the number of thermally populated rotational states in the clusters. We discuss that spin-rotational couplings allow for avoided crossings and a reduction in the effective magnetic moment of the cluster. This work attempts to understand the evolution of magnetic properties in isolated weakly bound clusters and is relevant to diamagnetic and paramagnetic species expected to exist in solvated electron systems.
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Synthesis and properties of cyclic sandwich compounds. Nature 2023; 620:92-96. [PMID: 37532814 DOI: 10.1038/s41586-023-06192-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 05/10/2023] [Indexed: 08/04/2023]
Abstract
Cyclic nanometre-scale sandwich complexes assembled from individual building blocks were synthesized. Sandwich complexes, in which a metal ion is π-coordinated by two planar aromatic organic rings belong to the foundations of organometallic chemistry. They have been successfully used in a wide variety of applications ranging from catalysis, synthesis and electrochemistry to nanotechnology, materials science and medicine1,2. Extending the sandwich structural motif leads to linear multidecker compounds, in which aromatic organic rings and metal atoms are arranged in an alternating fashion. However, the extension to a cyclic multidecker scaffold is unprecedented. Here we show the design, synthesis and characterization of an isomorphous series of circular sandwich compounds, for which the term 'cyclocenes' is suggested. These cyclocenes consist of 18 repeating units, forming almost ideally circular, closed rings in the solid state, that can be described by the general formula [cyclo-MII(μ-η8:η8-CotTIPS)]18 (M = Sr, Sm, Eu; CotTIPS = 1,4-(iPr3Si)2C8H62-). Quantum chemical calculations lead to the conclusion that a unique interplay between the ionic metal-to-ligand bonds, the bulkiness of the ligand system and the energy gain on ring closure, which is crucially influenced by dispersion interactions, facilitate the formation of these cyclic systems. Up to now, only linear one-dimensional multidecker sandwich compounds have been investigated for possible applications such as nanowires3-10. This textbook example of cyclic sandwich compounds is expected to open the door for further innovations towards new functional organometallic materials.
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Electron transfers’ assessment between stannol ring of triple-decker complexes and M(CO)5 (M = Cr, Mo, W), MnCp(CO)2 and CoCp(CO) metallic fragments: Bonding and energy decomposition analysis. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.115960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Using dianionic metallole ligands (silole or germole) and the cyclooctatetraendiide dianion, heteroleptic lanthanide multi-decker complexes have been prepared. Due to the heteroatom of the metallole ligands intermolecular bridging between the sandwich complexes takes place. Our work highlights that different combinations of the lanthanide and heterocycle lead to different intermolecular interactions including a dimeric La-silole sandwich complex, a La-germole ladder-type polymeric species and a Ce-germole coordination polymer.
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Selecting the Reaction Path in On-Surface Synthesis through the Electron Chemical Potential in Graphene. J Am Chem Soc 2022; 144:11003-11009. [PMID: 35695094 DOI: 10.1021/jacs.2c04359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The organometallic on-surface synthesis of the eight-membered sp2 carbon-based ring cyclooctatetraene (C8H8, Cot) with the neighboring rare-earth elements ytterbium and thulium yields fundamentally different products for the two lanthanides, when conducted on graphene (Gr) close to the charge neutrality point. Sandwich-molecular YbCot wires of more than 500 Å length being composed of an alternating sequence of Yb atoms and upright-standing Cot molecules result from the on-surface synthesis with Yb. In contrast, repulsively interacting TmCot dots consisting of a single Cot molecule and a single Tm atom result from the on-surface synthesis with Tm. While the YbCot wires are bound through van der Waals interactions to the substrate, the dots are chemisorbed to Gr via the Tm atoms being more electropositive compared to Yb atoms. When the electron chemical potential in Gr is substantially raised (n-doping) through backside doping from an intercalation layer, the reaction product in the synthesis with Tm can be tuned to TmCot sandwich-molecular wires rather than TmCot dots. By use of density functional theory, it is found that the reduced electronegativity of Gr upon n-doping weakens the binding as well as the charge transfer between the reaction intermediate TmCot dot and Gr. Thus, the assembly of the TmCot dots to long TmCot sandwich-molecular wires becomes energetically favorable. It is thereby demonstrated that the electron chemical potential in Gr can be used as a control parameter in an organometallic on-surface synthesis to tune the outcome of a reaction.
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Transport properties of MoS 2/V 7(Bz) 8 and graphene/V 7(Bz) 8 vdW junctions tuned by bias and gate voltages. RSC Adv 2022; 12:17422-17433. [PMID: 35765433 PMCID: PMC9189623 DOI: 10.1039/d2ra02196j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/06/2022] [Indexed: 12/02/2022] Open
Abstract
The MoS2/V7(Bz)8 and graphene/V7(Bz)8 vdW junctions are designed and the transport properties of their four-terminal devices are comparatively investigated based on density functional theory (DFT) and the nonequilibrium Green's function (NEGF) technique. The MoS2 and graphene nanoribbons act as the source-to-drain channel and the spin-polarized one-dimensional (1D) benzene-V multidecker complex nanowire (V7(Bz)8) serves as the gate channel. Gate voltages applied on V7(Bz)8 exert different influences of electron transport on MoS2/V7(Bz)8 and graphene/V7(Bz)8. In MoS2/V7(Bz)8, the interplay of source and gate bias potentials could induce promising properties such as negative differential resistance (NDR) behavior, output/input current switching, and spin-polarized currents. In contrast, the gate bias plays an insignificant effect on the transport along graphene in graphene/V7(Bz)8. This dissimilarity is attributed to the fact that the conductivity follows the sequence of MoS2 < V7(Bz)8 < graphene. These transport characteristics are examined by analyzing the conductivity, the currents, the local density of states (LDOS), and the transmission spectra. These results are valuable in designing multi-terminal nanoelectronic devices.
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A unique and discrete Ce( iii) macrocyclic complex exhibits ferroelectric, dielectric, and slow relaxation of magnetization properties. Inorg Chem Front 2022. [DOI: 10.1039/d2qi00369d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A [Ce(L1)(NO3)3] (1) was found to exhibit ferroelectric and magnetic bistability simultaneously. The ferroelectric to paraelectric transition was observed at 303 K and a small external electric field was required to switch the spontaneous polarization in 1.
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Metal cyclopropenylidene sandwich cluster and nanowire: structural, electronic, and magnetic properties. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:235301. [PMID: 33618336 DOI: 10.1088/1361-648x/abe8a0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Organometallic sandwich clusters and nanowires can offer prototypes for molecular ferromagnet and nanoscale spintronic devices due to the strong coupling of local magnetic moments in the nanowires direction and experimental feasibility. Here, on the basis of first-principles calculations, we reportTMn(c-C3H2)n+1(TM= Ti, Mn;n= 1-4) sandwich clusters and 1D [TM(c-C3H2)]∞sandwich nanowires building from transitional metal and the smallest aromatic carbene of cyclopropenylidene (c-C3H2). Based on the results of lattice dynamic and thermodynamic studies, we show that the magnetic moment of Mnn(c-C3H2)n+1clusters increases linearly with the number ofn, and 1D [Mn(c-C3H2)]∞nanowire is a stable ferromagnetic semiconductor, which can be converted into half metal with carrier doping. In contrary, both Tin(c-C3H2)n+1and 1D [Ti(c-C3H2)]∞nanowire are nonmagnetic materials. This study reveals the potential application of the [TM(c-C3H2)]∞nanowire in spintronics.
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Abstract
A triple-decker complex of tungsten, [(Cp*W)2{μ-η6:η6-B4H4Co2(CO)5}(H)2] (1; Cp* = η5-C5Me5), with a planar middle deck has been isolated by thermolysis of an in situ formed intermediate from the reaction of Cp*WCl4 and LiBH4 with Co2(CO)8. In addition, we have also isolated another triple-decker complex, [(Cp*W)2{μ-η6:η6-B5H5Fe(CO)3}(H)2] (4), having a puckered central ring, from a similar reaction with Fe2(CO)9. Clusters 1 and 4 are unprecedented examples of a triple-decker complex having a 24-valence electron with bridging hydrogen atoms.
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Abstract
A new Stern–Gerlach setup elucidates the spin relaxation dynamics of small weakly-bound Na(NH3)n clusters.
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Structural Evolution and Electronic Properties of TaSi n-/0 ( n = 2-15) Clusters: Size-Selected Anion Photoelectron Spectroscopy and Theoretical Calculations. J Phys Chem A 2020; 124:9818-9831. [PMID: 33198467 DOI: 10.1021/acs.jpca.0c09209] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The structural evolution and electronic properties of TaSin-/0 (n = 2-15) clusters are explored using anion photoelectron spectroscopy accompanied by quantum chemical calculations. The Ta atom in TaSin-/0 is inclined to interact with more Si atoms and has high coordination numbers. The theoretical calculations show that TaSi2-/0 have trianglur structures and TaSi3-/0 adopt pyramid structures, while the geometries of TaSin-/0 (n = 4-7) are all exohedral structures dominated by bipyramid-based configurations with the Ta atom face-capping the Sin motifs. TaSi8-/0 and TaSi9-10- have boat-shaped geometries, whereas TaSi9-10 neutrals adopt bipyramid-based geometries instead of boat-shaped ones. TaSi11- and TaSi12 are confirmed as the critical size of transiting from exohedral to endohedral structures for anionic and neutral clusters, respectively. TaSi12-15-/0 have pentagonal or hexagonal prism-based geometries. Natural population analysis shows that the electron transfers from Sin skeletons to Ta atom. The second-order energy differences (Δ2E) and incremental binding energy (ΔEI) values exhibit strong odd-even alternations, suggesting that the TaSin-odd-/0 clusters are more stable than the adjacent TaSin-even-/0 ones, except that TaSi12-/0 are more stable than TaSi11-/0 and TaSi13-/0.
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Spin Transport Properties of One-Dimensional Benzene Ligand Organobimetallic Sandwich Molecular Wires. ACS OMEGA 2020; 5:5534-5539. [PMID: 32201846 PMCID: PMC7081641 DOI: 10.1021/acsomega.0c00206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 02/26/2020] [Indexed: 06/10/2023]
Abstract
Organometallic sandwich complexes, composed of cyclic hydrocarbon ligands and transition-metal atoms, display unique physical and chemical properties. In this work, the electronic and spin transport properties of one-dimensional (1D) VBz2 ligand bimetallic sandwich complexes, VBz2-TM (TM = Cr, Mn, and Fe), are systematically investigated using density functional theory and nonequilibrium Green's function method. The results show that all the 1D infinite molecular wires [(VBz2)TM]∞ (TM = Cr-Fe) are found to be thermodynamically stable with high binding energies (∼1.0-3.45 eV). In particular, they are predicted to be ferromagnetic half metals. Moreover, the I-V curves exhibit negative differential resistance for one, two, and three VBz2-TM wires at TM = Cr, Mn, and Fe, respectively, which is of great significance for certain electronic applications. Our findings strongly suggest that the benzene ligand bimetallic sandwich molecular wires are good candidates for potential electronics and spintronics.
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Dynamical fluxionality, multiplicity of geometrical forms, and electronic properties of anionic, neutral, and cationic TanSi12 (n = 1–3) clusters: quantum chemical calculations. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1682209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Theoretical Study on Sandwich-Like Transition-Metal-Cyclooctatetraene Clusters and One-Dimensional Infinite Molecular Wires. ACS OMEGA 2019; 4:9739-9744. [PMID: 31460064 PMCID: PMC6648966 DOI: 10.1021/acsomega.9b00637] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 05/09/2019] [Indexed: 06/10/2023]
Abstract
Using density functional theory calculations, we investigated the structure and electronic properties of cyclooctatetraene (C8H8, COT)-ligand mono- or bi-transition-metal (M) sandwich clusters, M n (COT) n+1 (M = Sc, Ti, Cr, Mn, n = 1, 2) or (COT)M1(COT)M2(COT), as well as their one-dimensional infinite molecular wires. All the sandwich M-COT clusters and molecular wires are rather stable with their binding energies ranging from 3.20 to 7.48 eV per transition-metal atom. Superior to M n Bz n+1 complexes, most sandwich M-COT complexes are in their high spin states with ultrahigh magnetic moments. Moreover, one-dimensional infinite molecular wires, [Cr(COT)]∞, [(COT)V(COT)Ti]∞ and [(COT)Sc(COT)Cr]∞, are predicted to be ferromagnetic half-metals. Our findings suggest that such M-COT sandwich complexes may be potential candidates for applications in spintronics.
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A novel class of one-dimensional Ta 4TMTe 4 (TM = Cr, Fe, Co and Ni) compounds with strain-switched magnetic states. Phys Chem Chem Phys 2018; 20:6990-6995. [PMID: 29465728 DOI: 10.1039/c7cp07691f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The development of one-dimensional (1D) nanowires with controllable magnetic properties is important for spintronic applications. Herein, we systematically investigated the structural, electronic, and magnetic properties of 1D transition-metal (TM) compounds (Ta4TMTe4, TM = Cr, Fe, Co and Ni) through density functional theory (DFT) calculations. Ta4CrTe4 and Ta4FeTe4 are non-magnetic, while Ta4CoTe4 and Ta4NiTe4 are predicted to have antiferromagnetic ground states. Interestingly, uniaxial strain can induce nonmagnetism-ferromagnetism and nonmagnetism-antiferromagnetism transitions in Ta4CrTe4 and Ta4FeTe4 nanowires, respectively. Moreover, the antiferromagnetic ground states in Ta4CoTe4 and Ta4NiTe4 can be switched to ferromagnetic states through moderate strain. These strain-dependent magnetic moment and magnetic coupling transitions are related to the redistribution of d states in TM atoms. Our findings suggest a new route for facilitating the design of nanoelectronics and spintronics.
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Abstract
Lan(benzene) (n = 1 and 2) are formed in a pulsed laser-ablation molecular beam source and characterized by low-energy photoelectron imaging spectroscopy. The photoelectron spectrum of La2(benzene) displays a strong origin band, a short metal-ligand stretching progression, and a weak ring deformation band. Four isomers are considered for La2(benzene), and the preferred structure is an inverse sandwich with two La atoms residing on the opposite sides of the benzene ring. The ground electronic state of the inverse sandwich is 1A1g (D3d) with (5dxy,x2-y2 + π*)46s2 electron configuration. Ionization removes a La-based 6s electron and yields a 2A1g ion. The spectrum of La(benzene) is similar to the zero-electron kinetic energy spectrum reported previously by our group, although the spectral line width is somewhat broader. The measurement of the photoelectron angular distribution of La(benzene) confirms that the ejected electron has largely a p wave character. The metal-ligand bonding of La2(benzene) is considerably stronger than that of La(benzene) due to the threefold binding of each La atom in the dilanthanum species and the twofold binding in the monolanthanum complex.
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Half-Metallicity in One-Dimensional Metal Trihydride Molecular Nanowires. J Am Chem Soc 2017; 139:6290-6293. [DOI: 10.1021/jacs.7b01369] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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The structural and electronic properties of NbSi n-/0 (n = 3-12) clusters: anion photoelectron spectroscopy and ab initio calculations. NANOSCALE 2016; 8:19769-19778. [PMID: 27874133 DOI: 10.1039/c6nr07480d] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Niobium-doped silicon clusters, NbSin- (n = 3-12), were generated by laser vaporization and investigated by anion photoelectron spectroscopy. The structures and electronic properties of NbSin- anions and their neutral counterparts were investigated with ab initio calculations and compared with the experimental results. It is found that the Nb atom in NbSin-/0 prefers to occupy the high coordination sites to form more Nb-Si bonds. The most stable structures of NbSi3-7-/0 are all exohedral structures with the Nb atom face-capping the Sin frameworks. At n = 8, both the anion and neutral adopt a boat-shaped structure and the openings of the boat-shaped structures remain unclosed in NbSi9-10-/0 clusters. The most stable structure of the NbSi11- anion is endohedral, while that of neutral NbSi11 is exohedral. The global minima of both the NbSi12- anion and neutral NbSi12 are D6h symmetric hexagonal prisms with the Nb atom at the center. The perfect D6h symmetric hexagonal prism of NbSi12- is electronically stable as it obeys the 18-electron rule and has a shell-closed electronic structure with a large HOMO-LUMO gap of 2.70 eV. The molecular orbital analysis of NbSi12- suggests that the delocalized Nb-Si12 ligand interactions may contribute to the stability of the D6h symmetric hexagonal prism. The AdNDP analysis shows that the delocalized 2c-2e Si-Si bonds and multicenter-2e NbSin bonds are important for the structural stability of the NbSi12- anion.
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Size-Dependent Ligand Quenching of Ferromagnetism in Co 3(benzene) n+ Clusters Studied with X-ray Magnetic Circular Dichroism Spectroscopy. J Phys Chem Lett 2016; 7:4568-4575. [PMID: 27779876 DOI: 10.1021/acs.jpclett.6b01839] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Cobalt-benzene cluster ions of the form Co3(bz)n+ (n = 0-3) were produced in the gas phase, mass-selected, and cooled in a cryogenic ion trap held at 3-4 K. To explore ligand effects on cluster magnetic moments, these species were investigated with X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy. XMCD spectra yield both the spin and orbital angular momenta of these clusters. Co3+ has a spin magnetic moment of μS = 6 μB and an orbital magnetic moment of μL = 3 μB. Co3(bz)+ and Co3(bz)2+ complexes were found to have spin and orbital magnetic moments identical to the values for ligand-free Co3+. However, coordination of the third benzene to form Co3(bz)3+ completely quenches the high spin state of the system. Density functional theory calculations elucidate the spin states of the Co3(bz)n+ species as a function of the number of attached benzene ligands, explaining the transition from septet to singlet for n = 0 → 3.
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Effects of valence, geometry and electronic correlations on transport in transition metal benzene sandwich molecules. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:445301. [PMID: 27605217 DOI: 10.1088/0953-8984/28/44/445301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We study the impact of the valence and the geometry on the electronic structure and transport properties of different transition metal-benzene sandwich molecules bridging the tips of a Cu nanocontact. Our density-functional calculations show that the electronic transport properties of the molecules depend strongly on the molecular geometry which can be controlled by the nanocontact tips. Depending on the valence of the transition metal center certain molecules can be tuned in and out of half-metallic behaviour facilitating potential spintronics applications. We also discuss our results in the framework of an Anderson impurity model, indicating cases where the inclusion of local correlations alters the ground state qualitatively. For Co and V centered molecules we find indications of an orbital Kondo effect.
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Cooperative Effects in Clusters and Oligonuclear Complexes of Transition Metals in Isolation. STRUCTURE AND BONDING 2016. [DOI: 10.1007/430_2016_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Multiple-decker and ring sandwich formation of manganese-benzene organometallic cluster anions: Mn nBz n- (n = 1-5 and 18). Phys Chem Chem Phys 2016; 18:26049-26056. [PMID: 27711615 DOI: 10.1039/c6cp05380g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Organometallic multiple-decker sandwich clusters are topics of great interest due to their unique electronic and magnetic properties originating from anisotropic structures. We report a joint anion photoelectron spectroscopic and computational study on a new family of manganese (Mn)-benzene (Bz) anionic clusters MnnBzn-. In stark contrast to the most widely studied vanadium-Bz sandwich clusters, it is found that MnnBzn- (n = 1-5) clusters exhibit unprecedented multiple-decker structures with a tilted Mn-Bz stacking and a monotonically increasing behavior of their high spin multiplicities. Furthermore, a couple of closed ring forms of Mn18Bz18- and its neutral state are computationally anticipated as an intriguing "cluster of Mn1Bz1 clusters" in which the neutral Mn18Bz18 has extremely high C18h symmetry with an uncommon spin state of 2S + 1 = 55. The extensively delocalized electron environment of Mn18Bz18 allows the simple Hückel model to reveal the strong intra-atomic exchange interactions within the Mn 3d electrons.
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Theoretical study on interactions of N-heterocyclic carbene with the bare first-row transition metals. Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-1922-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
The electronic structure of a novel inorganic (8, 8) MoS2 nanotube nanocable, (VBz)n@MoS2NT, (where Bz refers as C6H6), is investigated using density functional theory. Transport property calculations are further performed employing non-equilibrium Green's function methods by modeling a two-probe device with a finite-sized nanocable sandwiched between two electrodes of its own. It is found that the transport properties of the nanocable agree well with its electronic structure. The core (VBz)n nanowire in the (VBz)n@MoS2NT plays a significant role in electron transportation, meanwhile, the sheath MoS2NT also participates in electron transportation. This phenomenon is different from those of (VBz)n@CNT and (VBz)n@BNNT nanocables. For the (VBz)n@CNT, the transport properties are majorly dominated by the metallic CNT sheath, while for the (VBz)n@BNNT, it is merely decided by the core (VBz)n. The conductivity of the (VBz)n@MoS2NT is slightly better in comparison with pure (VBz)n. Similar to pure (VBz)n, the (VBz)n@MoS2NT shows spin-polarized transport properties: the spin-down state gives a higher conductivity than the spin-up state. The values of the spin filter efficiency of the (VBz)n@MoS2NT can be up to >80%, indicating it to be a good candidate for spin filters. In addition, it is also found that encapsulating (VBz)n into the MoS2NT could introduce magnetism. More importantly, the ferromagnetic (VBz)n@MoS2NT is thermally rather stable. Therefore, encapsulating (VBz)n into the MoS2NT can effectively tune the electronic and transport properties for exploring novel functional nanodevices.
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Abstract
The manipulation of the molecular spin state by atom doping is an attractive strategy to confer desirable magnetic properties to molecules. Here, we present the formation of novel magnetic metallocenes by following this approach. In particular, two different on-surface procedures to build isolated and layer-integrated Co-ferrocene (CoFc) molecules on a metallic substrate via atomic manipulation and atom deposition are shown. The structure as well as the electronic properties of the so-formed molecule are investigated combining scanning tunneling microscopy and spectroscopy with density functional theory calculations. It is found that unlike single ferrocene a CoFc molecule possesses a magnetic moment as revealed by the Kondo effect. These results correspond to the first controlled procedure toward the development of tailored metallocene-based nanowires with a desired chemical composition, which are predicted to be promising materials for molecular spintronics.
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Abstract
Novel nanocables with [V(Bz)2]n inside SWCNT and DWCNT.
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An electron-poor di-molybdenum triple-decker with a puckered [B4Ru2] bridging ring is an oblato-closo cluster. Chem Commun (Camb) 2015; 51:3828-31. [PMID: 25648449 DOI: 10.1039/c4cc09630d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An unprecedented, 22-valence-electron triple-decker sandwich complex [(Cp*Mo)2{μ-η(6):η(6)-B4H4Ru2(CO)6}], 2, has been prepared. In an effort to generate analogous triple-deckers with group 6 metal carbonyl fragments in the middle deck, we have isolated [(Cp*MoCO)2(μ-H)2B4H4], 3, that provides the first direct evidence for the missing link between [(Cp*MoCl)2B3H7] and [(Cp*Mo)2B5H9] clusters.
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Experimental and theoretical studies of the structural and electronic properties of vanadium-benzene sandwich clusters and their anions: V(n)Bz(n)(0/-) (n = 1-5) and V(n)Bz(n-1)(0/-) (n = 2-5). J Chem Phys 2014; 141:214304. [PMID: 25481141 DOI: 10.1063/1.4902367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
One end open V(n)Bz(n)(-) (n = 1-5; Bz = benzene) and both ends open V(n)Bz(n-1)(-) (n = 2-5) vanadium-benzene cluster anions were studied using anion photoelectron spectroscopy and density functional calculations. The smaller (n ≤ 3) V(n)Bz(n) and V(n)Bz(n-1) clusters and corresponding anions were found to have structural isomers, whereas full-sandwiched V(n)Bz(n+1) clusters preferred to form multiple-decker sandwich structures. Several isomeric V2Bz2 structures were identified theoretically and the anion photoelectron spectra of V2Bz2(0/-) were explained well by the coexistence of two isomeric structures: (1) a V2-core structure sandwiched between benzene molecules and (2) an alternating sandwich structure with the spin state strongly dependent on the structure. The adiabatic electron affinity of both V(n)Bz(n) and V(n)Bz(n-1) was found to increase with the cluster size at larger sizes (n = 4 or 5) and approaches to that of V(n)Bz(n+1). The evolution of the structural and electronic properties of V(n)Bz(m) and V(n)Bz(m)(-) (m = n and n - 1) with size is discussed in comparison with V(n)Bz(n+1) and V(n)Bz(n+1)(-).
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Abstract
Understanding the bonding between silicon and transition metals is valuable for devising strategies for incorporating magnetic species into silicon. CrSi12 is the standard example of a cluster whose apparent high stability has been explained by the 18-electron rule. We critically examine the bonding and nature of stability of CrSi12 and show that its electronic structure does not conform to the 18-electron rule. Through theoretical studies, we find that CrSi12 has 16 effective valence electrons assigned to the Cr atom and an unoccupied 3dz(2) orbital. We demonstrate that the cluster's apparent stability is rooted in a crystal field-like splitting of the 3d orbitals analogous to that of square planar complexes. CrSi14 is shown to follow the 18-electron rule and exhibits all conventional markers characteristic of a magic cluster.
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Formation and Electronic Structures of Organoeuropium Sandwich Nanowires. J Phys Chem A 2014; 118:8298-308. [DOI: 10.1021/jp5011007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Structural and Electronic Properties of TMn[(BN)3H6]m Complexes with TM = Co (n, m = 1–3) and with TM = Fe, Ni, Ru, Rh, Pd (n = m = 1–3). J Phys Chem A 2014; 118:2976-83. [DOI: 10.1021/jp500191v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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37
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Size-dependent magnetic order and giant magnetoresistance in organic titanium-benzene multidecker cluster. Phys Chem Chem Phys 2014; 16:1902-8. [PMID: 24336893 DOI: 10.1039/c3cp54352h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Using density functional theory and non-equilibrium Green's function method, we investigated the magnetic and transport properties of small organic titanium-benzene sandwich clusters TinBzn+1 (n = 1-3). The results show that TiBz2 is nonmagnetic while Ti2Bz3 and Ti3Bz4 are ferromagnetic, and our prediction is in agreement with experimental observation. The double exchange mechanism plays a key role in the ferromagnetism of larger clusters. With Ni as the two electrodes, significant spin-filter efficiency (SFE) and giant magnetoresistance (GMR) were found in the TinBzn+1 molecular junction. These transport properties could be controlled by cluster size, bias voltage or gate voltage. Specially, a sign-reversible GMR effect was observed in the Ti2Bz3 molecular junction. Finally, the microscopic mechanisms of SFE and GMR were suggested.
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Perfect spin filtering and large spin thermoelectric effects in organic transition-metal molecular junctions. Phys Chem Chem Phys 2014; 16:11349-55. [DOI: 10.1039/c4cp00390j] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Theoretical investigations on structural, electronic, and magnetic properties of TM2Np2 (Np=Naphthalene, TM=Sc–Ni) sandwich clusters. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2013.02.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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[(B3O3H3)(n)M]+ (n = 1, 2;M = Cu, Ag, Au): a new class of metal-cation complexes. J Mol Model 2013; 19:3219-24. [PMID: 23636641 DOI: 10.1007/s00894-013-1846-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/02/2013] [Indexed: 10/26/2022]
Abstract
A density functional theory (DFT) investigation into the structures and bonding characteristics of [(B3O3H3)nM](+)(n = 1, 2;M = Cu, Ag, Au) complexes was performed. DFT calculations and natural bond orbital (NBO) analyses indicate that the ΙB metal complexes of boroxine exhibit intriguing bonding characteristics, different from the typical cation-π interactions between ΙB metal-cations and benzene. The complexes of [B3O3H3M](+) and [(B3O3H3)2 M](+) (M = Cu, Ag, and Au) favor the conformation of perfectly planar structures with the C2v and D2h symmetry along one of the threefold molecular axes of boroxine, respectively. Detailed natural resonance theory (NRT) and canonical molecular orbitals (CMOs) analyses show that interaction between the metal cation and the boroxine in [B3O3H3M](+) (M = Cu, Ag, and Au) is mainly ionic, while the ΙB metal-cations←π donation effect is responsible for the binding site. In these complexes, boroxine serves as terminals η(1)-B3O3H3 with one O atom of the B3O3 ring. The infra-red (IR) spectra of [B3O3H3M](+) were simulated to facilitate their future experimental characterization. The complexes all give two IR active modes at about 1,300 and 2,700 cm(-1), which are inactive in pure boroxine. Simultaneously, the B-H stretching modes of the complexes are red-shifted due to the interaction between the metal-cation and boroxine. To explore the possibility of the structural pattern developed in this work forming mesoporous materials, complexes [(B3O3H3M)6](6+) (M = Cu, Ag, and Au) were also studied, which appear to be unique and particular interesting: they are all true minima with D6h symmetries and pore sizes ranging from 12.04 Å to 13.65 Å.
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Study on Electronic Properties of Composite Clusters toward Nanoscale Functional Advanced Materials. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2013. [DOI: 10.1246/bcsj.20120298] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Experimental and theoretical studies on the electronic properties of vanadium-benzene sandwich cluster anions, VnBzn+1− (n = 1-5). J Chem Phys 2012; 137:224305. [DOI: 10.1063/1.4769776] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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46
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Boratabenzene-vanadium sandwich molecular wire and its properties. NANOSCALE 2012; 4:7557-7562. [PMID: 23108175 DOI: 10.1039/c2nr31889j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Different from all reported sandwich molecular wires (SMWs), a novel class of SMW including vanadium boratabenzene (HBBz) clusters and their related one-dimensional (1D) SMWs are explored by using a density functional theory approach. The uniqueness of this class of SMWs lies in the boron heterocycles, where they possess a reactive functional atom. These features may overcome the limitation of existing SMWs which are inert and are difficult to be absorbed stably on surfaces. Theoretical calculations of the novel vanadium boratabenzene clusters indicated that they are energetically stable, with the rings having a restricted degree of rotation. In addition, its metallic 1D analog shows great promise in the applications of molecular electronics and spintronics.
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Multi-decker tricarbonyl-bridged sandwich complexes of transition metals: structure, stability and electron-counting rules. Phys Chem Chem Phys 2012; 14:14803-9. [PMID: 22806422 DOI: 10.1039/c2cp41839h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Structures and stabilities of a new family of multi-decker tricarbonyl-bridged sandwich complexes of transition metals (Cr, Mn, Fe) have been studied using DFT B3LYP/6-311+G(df,p) calculations. Stable structures satisfy the (12n + 6) electron-counting rule, where n is the number of metal atoms. Lengthening of the molecular chains is accompanied by growth of aromaticity of the inner basal cycles, lowering of the aromaticity of the terminal basal cycles and decrease in the energy gap between the frontier orbitals.
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The magnetic and quantum transport properties of benzene-vanadium-borazine mixed sandwich clusters: a new kind of spin filter. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:445501. [PMID: 23044517 DOI: 10.1088/0953-8984/24/44/445501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Using density functional theory and the non-equilibrium Green's function technique, we performed theoretical investigations on the magnetic and quantum transport properties of benzene-vanadium-borazine mixed organic/inorganic ligand sandwich clusters. The calculated results show that these finite sandwich clusters coupled to Ni electrodes exhibit novel quantum transport properties such as half-metallicity, negative differential resistance and spin-reversal effect, and can be viewed as a new kind of spin filter. However, for the infinite molecular wire, the ground state was identified as a ferromagnetic semiconductor with high stability. These findings suggest that the mixed organic/inorganic ligand sandwich clusters and molecular wires are promising materials for application in molecular electronics and spintronics.
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Structures and magnetism of multinuclear vanadium-pentacene sandwich clusters and their 1D molecular wires. J Chem Phys 2012; 137:164309. [PMID: 23126712 DOI: 10.1063/1.4759505] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Two types of multinuclear sandwich clusters, (V(3))(n)Pen(n+1), (V(4))(n)Pen(n+1) (Pen = Pentacene; n = 1, 2), and their corresponding infinite one-dimensional (1D) molecular wires ([V(3)Pen](∞), [V(4)Pen](∞)) are investigated theoretically, especially on their magnetic coupling mechanism. These sandwich clusters and molecular wires are found to be of high stability and exhibit intriguing magnetic properties. The intra-layered V atoms in (V(3))(n)Pen(n+1) clusters prefer antiferromagnetic (AFM) coupling, while they can be either ferromagnetic (FM) or AFM coupling in (V(4))(n)Pen(n+1) depending on the intra-layered V-V distances via direct exchange or superexchange mechanism. The inter-layered V atoms favor FM coupling in (V(3))(2)Pen(3), whereas they are AFM coupled in (V(4))(2)Pen(3). Such magnetic behaviors are the consequence of the competition between direct exchange and superexchange interactions among inter-layered V atoms. In contrast, the 1D molecular wires, [V(3)Pen](∞) and [V(4)Pen](∞), appear to be FM metallic with ultra high magnetic moments of 6.8 and 4.0 μ(B) per unit cell respectively, suggesting that they can be served as good candidates for molecular magnets.
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From Vanadium Naphthalene (Vn–1Npn) Sandwich Clusters to VNp Sandwich Nanowire: Structural, Energetic, Electronic, and Magnetic Properties. J Phys Chem A 2012; 116:1648-54. [DOI: 10.1021/jp2099398] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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