showing 31 related works from this author
Rare‐earth cyclobutadienyl sandwich complexes: Synthesis, structure and dynamic magnetic properties
2018
The potassium cyclobutadienyl [K2{η4‐C4(SiMe3)4}] (1) reacts with MCl3(THF)3.5 (M=Y, Dy) to give the first rare‐earth cyclobutadienyl complexes, that is, the complex anions [M{η4‐C4(SiMe3)4}{η4‐C4(SiMe3)3‐κ‐(CH2SiMe2}]2−, (2M), as their dipotassium salts. The tuck‐in alkyl ligand in 2M is thought to form through deprotonation of the “squarocene” complexes [M{η4‐C4(SiMe3)4}2]− by 1. Complex 2Dy is a single‐molecule magnet, but with prominent quantum tunneling. An anisotropy barrier of 323(22) cm−1 was determined for 2Dy in an applied field of 1 kOe, and magnetic hysteresis loops were observed up to 7 K. nonPeerReviewed
Carbonyl Back-Bonding Influencing the Rate of Quantum Tunnelling in a Dysprosium Metallocene Single-Molecule Magnet.
2019
The isocarbonyl-ligated metallocene coordination polymers [Cp*2M(μ-OC)W(Cp)(CO)(μ-CO)]∞ were synthesized with M = Gd (1, L = THF) and Dy (2, no L). In a zero direct-current field, the dysprosium version 2 was found to be a single-molecule magnet (SMM), with analysis of the dynamic magnetic susceptibility data revealing that the axial metallocene coordination environment leads to a large anisotropy barrier of 557(18) cm–1 and a fast quantum-tunnelling rate of ∼3.7 ms. Theoretical analysis of two truncated versions of 2, [Cp*2Dy{(μ-OC)W(Cp)(CO)2}2]− (2a), and [Cp*2Dy(OC)2]+ (2b), in which the effects of electron correlation outside the 4f orbital space were studied, revealed that tungsten-to-…
A three-coordinate iron–silylene complex stabilized by ligand–ligand dispersion forces
2016
The structural and bonding properties of a three-coordinate N-heterocyclic silyene (NHSi) complex of the iron(II) amide [Fe{N(SiMe3)2}2] are reported. Computational studies reveal that dispersion forces between the amido SiMe3 substituents and the isopropyl substituents on the NHSi ligand significantly enhance the stability of the complex, along with Fe-to-Si π-backbonding.
A Dysprosium Metallocene Single-Molecule Magnet Functioning at the Axial Limit
2017
Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] (1Dy Cpttt=1,2,4‐tri(tert‐butyl)cyclopentadienide) by the triethylsilylium cation produces the first base‐free rare‐earth metallocenium cation [(Cpttt)2Dy]+ (2Dy) as a salt of the non‐coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low‐lying Kramers doub…
Open-shell doublet character in a hexaazatrinaphthylene trianion complex
2015
Three-electron reduction of hexaazatrinaphthylene (HAN) with a magnesium(I) reagent leads to [(HAN){Mg(nacnac)}3] (1), containing a [HAN]3– ligand with a spin of S = ½. Ab initio calculations reveal that the [HAN]3– ligand in 1 has a groundstate wave function with multiconfigurational properties, and can be described as a triradicaloid species with a small amount of open-shell doublet character. peerReviewed
Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet
2018
Breaking through the nitrogen ceiling Single-molecule magnets could prove useful in miniaturizing a wide variety of devices. However, their application has been severely hindered by the need to cool them to extremely low temperature using liquid helium. Guo et al. now report a dysprosium compound that manifests magnetic hysteresis at temperatures up to 80 kelvin. The principles applied to tuning the ligands in this complex could point the way toward future architectures with even higher temperature performance. Science , this issue p. 1400
Uranocenium: Synthesis, Structure, and Chemical Bonding
2019
Abstraction of iodide from [(η5 -C5 i Pr5 )2 UI] (1) produced the cationic uranium(III) metallocene [(η5 -C5 i Pr5 )2 U]+ (2) as a salt of [B(C6 F5 )4 ]- . The structure of 2 consists of unsymmetrically bonded cyclopentadienyl ligands and a bending angle of 167.82° at uranium. Analysis of the bonding in 2 showed that the uranium 5f orbitals are strongly split and mixed with the ligand orbitals, thus leading to non-negligible covalent contributions to the bonding. Investigation of the dynamic magnetic properties of 2 revealed that the 5f covalency leads to partially quenched anisotropy and fast magnetic relaxation in zero applied magnetic field. Application of a magnetic field leads to domin…
Isolation of a perfectly linear uranium(II) metallocene
2020
Reduction of the uranium(III) metallocene [(eta(5)-(C5Pr5)-Pr-i)(2)UI] (1) with potassium graphite produces the "second-generation" uranocene [(eta(5)-(C5Pr5)-Pr-i)(2)U] (2), which contains uranium in the formal divalent oxidation state. The geometry of 2 is that of a perfectly linear bis(cyclopentadienyl) sandwich complex, with the ground-state valence electron configuration of uranium(II) revealed by electronic spectroscopy and density functional theory to be 5f(3) 6d(1). Appreciable covalent contributions to the metal-ligand bonds were determined from a computational study of 2, including participation from the uranium 5f and 6d orbitals. Whereas three unpaired electrons in 2 occupy orbi…
Uranium( iv ) cyclobutadienyl sandwich compounds: synthesis, structure and chemical bonding
2019
The 1 : 1 reactions of uranium(IV) tetrakis(borohydride) with the sodium and potassium salts of the cyclobutadienyl anion [C4(SiMe3)4]2− (Cb′′′′) produce the half-sandwich complexes [Na(12-crown-4)2][U(η4-Cb′′′′)(BH4)3] and [U(η4-Cb′′′′)(μ-BH4)3{K(THF)2}]2. In the 1 : 2 reaction of U(BH4)4 with Na2Cb′′′′, formation of [U(η4-Cb′′′′)(η3-C4H(SiMe3)3-κ-(CH2SiMe2)(BH4))]− reveals that a Cb′′′′ ligand undergoes an intramolecular deprotonation, resulting in an allyl/tuck-in bonding mode. A computational study reveals that the uranium–Cb′′′′ bonding has an appreciable covalent component with contributions from the uranium 5f and 6d orbitals. peerReviewed
Thermal expansion and magnetic properties of benzoquinone-bridged dinuclear rare-earth complexes.
2017
The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl2·THF3)2] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of …
Strong Exchange Coupling in a Trimetallic Radical-Bridged Cobalt(II)-Hexaazatrinaphthylene Complex
2016
: Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18-c-6 produces [{K(18-c-6)}HAN], which contains the S = 1/2 radical [HAN]C ¢ . The [HAN]C ¢ radical can be transferred to the cobalt(II) amide [Co{N- (SiMe3 )2 }2 ], forming [K(18-c-6)][(HAN){Co(N’’)2 }3 ]; magnetic measurements on this compound reveal an S = 4 spin system with strong cobalt–ligand antiferromagnetic exchange and J ¢290 cm¢1 (¢2 J formalism). In contrast, the CoII centres in the unreduced analogue [(HAN){Co(N’’)2}3] are weakly coupled (J ¢4.4 cm¢1 ). The finding that [HAN]C ¢ can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on str…
A three-coordinate iron–silylene complex stabilized by ligand–ligand dispersion forces
2016
The structural and bonding properties of a three-coordinate N-heterocyclic silyene (NHSi) complex of the iron(II) amide [Fe{N(SiMe3)2}2] are reported. Computational studies reveal that dispersion forces between the amido SiMe3 substituents and the isopropyl substituents on the NHSi ligand significantly enhance the stability of the complex, along with Fe-to-Si π-backbonding. peerReviewed
CCDC 1966630: Experimental Crystal Structure Determination
2019
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CCDC 1854466: Experimental Crystal Structure Determination
2018
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CCDC 1955865: Experimental Crystal Structure Determination
2020
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CCDC 1854468: Experimental Crystal Structure Determination
2018
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CCDC 1833613: Experimental Crystal Structure Determination
2018
Related Article: Alexander F. R. Kilpatrick, Fu-Sheng Guo, Benjamin M. Day, Akseli Mansikkamäki, Richard A. Layfield, F. Geoffrey N. Cloke|2018|Chem.Commun.|54|7085|doi:10.1039/C8CC03516D
CCDC 1966628: Experimental Crystal Structure Determination
2019
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CCDC 1833614: Experimental Crystal Structure Determination
2018
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CCDC 1047819: Experimental Crystal Structure Determination
2015
Related Article: Jani O. Moilanen, Benjamin M. Day, Thomas Pugh, Richard A. Layfield|2015|Chem.Commun.|51|11478|doi:10.1039/C5CC04004C
CCDC 1840738: Experimental Crystal Structure Determination
2018
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CCDC 1966629: Experimental Crystal Structure Determination
2019
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CCDC 1463752: Experimental Crystal Structure Determination
2016
Related Article: Mikko M. Hänninen, Kuntal Pal, Benjamin M. Day, Thomas Pugh, Richard A. Layfield|2016|Dalton Trans.|45|11301|doi:10.1039/C6DT02486F
CCDC 1557625: Experimental Crystal Structure Determination
2017
Related Article: Jani O. Moilanen, Akseli Mansikkamäki, Manu Lahtinen, Fu-Sheng Guo, Elina Kalenius, Richard A. Layfield, Liviu F. Chibotaru|2017|Dalton Trans.|46|13582|doi:10.1039/C7DT02565C
CCDC 1840737: Experimental Crystal Structure Determination
2018
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CCDC 1557624: Experimental Crystal Structure Determination
2017
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CCDC 1955866: Experimental Crystal Structure Determination
2020
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CCDC 1557623: Experimental Crystal Structure Determination
2017
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CCDC 1854467: Experimental Crystal Structure Determination
2018
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CCDC 1840739: Experimental Crystal Structure Determination
2018
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CCDC 1840736: Experimental Crystal Structure Determination
2018
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