I19-Small Molecule Single Crystal Diffraction
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Grigore A.
Timco
,
Antonio
Fernandez
,
Andreas K.
Kostopoulos
,
Jodie F.
Charlton
,
Selena J.
Lockyer
,
Thomas R.
Hailes
,
Ralph W.
Adams
,
Eric J. L.
Mcinnes
,
Floriana
Tuna
,
Iñigo J.
Vitorica-yrezabal
,
George F. S.
Whitehead
,
Richard E. P.
Winpenny
Diamond Proposal Number(s):
[17379]
Abstract: [2] and [3] hybrid rotaxanes are reported based on {Ti7M} rings (M is a trivalent metal such as FeIII or GaIII). NMR studies show that [2]rotaxanes can act as molecular shuttles, while EPR studies of [3]rotaxanes show weak interactions between the paramagnetic components of the supramolecular assemblies.
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Aug 2018
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Ashley J.
Wooles
,
David P.
Mills
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Gareth T. W.
Law
,
Adam J.
Fuller
,
Felipe
Kremer
,
Mark
Ridgway
,
William
Lewis
,
Laura
Gagliardi
,
Bess
Vlaisavljevich
,
Stephen T.
Liddle
Diamond Proposal Number(s):
[9621, 13559]
Open Access
Abstract: Despite the fact that non-aqueous uranium chemistry is over 60 years old, most polarised-covalent uranium-element multiple bonds involve formal uranium oxidation states IV, V, and VI. The paucity of uranium(III) congeners is because, in common with metal-ligand multiple bonding generally, such linkages involve strongly donating, charge-loaded ligands that bind best to electron-poor metals and inherently promote disproportionation of uranium(III). Here, we report the synthesis of hexauranium-methanediide nanometre-scale rings. Combined experimental and computational studies suggest overall the presence of formal uranium(III) and (IV) ions, though electron delocalisation in this Kramers system cannot be definitively ruled out, and the resulting polarised-covalent U = C bonds are supported by iodide and δ-bonded arene bridges. The arenes provide reservoirs that accommodate charge, thus avoiding inter-electronic repulsion that would destabilise these low oxidation state metal-ligand multiple bonds. Using arenes as electronic buffers could constitute a general synthetic strategy by which to stabilise otherwise inherently unstable metal-ligand linkages.
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May 2018
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I19-Small Molecule Single Crystal Diffraction
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Sergio
Sanz
,
Helen M.
O'connor
,
Priyanka
Comar
,
Amgalanbaatar
Baldansuren
,
Mateusz B.
Pitak
,
Simon J.
Coles
,
Høgni
Weihe
,
Nicholas F.
Chilton
,
Eric J. L.
Mcinnes
,
Paul J.
Lusby
,
Stergios
Piligkos
,
Euan K.
Brechin
Diamond Proposal Number(s):
[11238]
Abstract: The reaction of the simple metalloligand [FeIIIL3] [HL = 1-(4-pyridyl)butane-1,3-dione] with a variety of different MII salts results in the formation of a family of heterometallic cages of formulae [FeIII8PdII6L24]Cl12 (1), [FeIII8CuII6L24(H2O)4Br4]Br8 (2), [FeIII8CuII6L24(H2O)10](NO3)12 (3), [FeIII8NiII6L24(SCN)11Cl] (4), and [FeIII8CoII6L24(SCN)10(H2O)2]Cl2 (5). The metallic skeleton of each cage describes a cube in which the FeIII ions occupy the eight vertices and the MII ions lie at the center of the six faces. Direct-current magnetic susceptibility and magnetization measurements on 3–5 reveal the presence of weak antiferromagnetic exchange between the metal ions in all three cases. Computational techniques known in theoretical nuclear physics as statistical spectroscopy, which exploit the moments of the Hamiltonian to calculate relevant thermodynamic properties, determine JFe–Cu = 0.10 cm–1 for 3 and JFe–Ni = 0.025 cm–1 for 4. Q-band electron paramagnetic resonance spectra of 1 reveal a significantly wider spectral width in comparison to [FeL3], indicating that the magnitude of the FeIII zero-field splitting is larger in the heterometallic cage than in the monomer.
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Jan 2018
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B22-Multimode InfraRed imaging And Microspectroscopy
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Zhenzhong
Lu
,
Harry G. W.
Godfrey
,
Ivan
Da Silva
,
Yongqiang
Cheng
,
Mathew
Savage
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Simon J.
Teat
,
Kevin J.
Gagnon
,
Mark D.
Frogley
,
Pascal
Manuel
,
Svemir
Rudic
,
Anibal J.
Ramirez-cuesta
,
Timothy L.
Easun
,
Sihai
Yang
,
Martin
Schröder
Diamond Proposal Number(s):
[13666]
Open Access
Abstract: Hydrogen bonds dominate many chemical and biological processes, and chemical modification enables control and modulation of host–guest systems. Here we report a targeted modification of hydrogen bonding and its effect on guest binding in redox-active materials. MFM-300(VIII) {[VIII2(OH)2(L)], LH4=biphenyl-3,3′,5,5′-tetracarboxylic acid} can be oxidized to isostructural MFM-300(VIV), [VIV2O2(L)], in which deprotonation of the bridging hydroxyl groups occurs. MFM-300(VIII) shows the second highest CO2 uptake capacity in metal-organic framework materials at 298 K and 1 bar (6.0 mmol g−1) and involves hydrogen bonding between the OH group of the host and the O-donor of CO2, which binds in an end-on manner, =1.863(1) Å. In contrast, CO2-loaded MFM-300(VIV) shows CO2 bound side-on to the oxy group and sandwiched between two phenyl groups involving a unique ···c.g.phenyl interaction [3.069(2), 3.146(3) Å]. The macroscopic packing of CO2 in the pores is directly influenced by these primary binding sites.
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Jan 2017
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I19-Small Molecule Single Crystal Diffraction
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Jesus
Ferrando Soria
,
Samantha a.
Magee
,
Alessandro
Chiesa
,
Stefano
Carretta
,
Paolo
Santini
,
Inigo
Vitorica-yrezabal1
,
Floriana
Tuna
,
George F. S.
Whitehead
,
Stephen
Sproules
,
Kyle m.
Lancaster
,
Anne-laure
Barra
,
Grigore a.
Timco
,
Eric J. L.
Mcinnes
,
Richard e. P.
Winpenny
Open Access
Abstract: Quantum information processing (QIP) could revolutionize how we simulate and understand quantum systems. Any QIP scheme requires both individual units (qubits) that have long phase memories and switchable units that can be placed between the qubits. Here, we describe supramolecular systems where {Cr7Ni} rings are used as qubits, linked by redox-switchable {Ru2M} oxo-centered triangles (M = Zn, Ni, or Co). The supramolecular assemblies have been structurally characterized and involve two {Cr7Ni} rings bound to {Ru2M} triangles through iso-nicotinate ligands. Detailed physical studies, including electrochemistry and electron paramagnetic resonance spectroscopy, show that when M = Co, the supramolecular assembly has the physical characteristics needed to implement the √iSWAP gate, which is an important entangling two-qubit gate. Detailed simulations show that the fidelity of this gate is potentially very high and depends on the phase memory time of the {Cr7Ni} qubits but not the {Ru2Co} switch.
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Nov 2016
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[9205]
Abstract: The effect of pressure on the intranuclear M···M separation and intermolecular
secondary interactions in the dinuclear chromium Pacman complex [Cr2(L)](C6H6) was
evaluated because this compound contains both a short Cr···Cr separation and an exogenously
bound molecule of benzene in the solid state. The electronic structure of [Cr2(L)] was
determined by electron paramagnetic resonance spectroscopy, SQUID magnetometry, and
density functional theory calculations and shows a diamagnetic ground state through
antiferromagnetic exchange, with no evidence for a Cr−Cr bond. Analysis of the solid-state
structures of [Cr2(L)](C6H6) at pressures varying from ambient to 3.0 GPa shows little
deformation in the Cr···Cr separation, i.e., no Cr−Cr bond formation, but instead a significantly increased interaction between
the exogenous arene and the chromium iminopyrrolide environment. It is therefore apparent from this analysis that [Cr2(L)]
would be best exploited as a rigid chemical synthon, with pressure regulation being used to mediate the approach and secondary
interactions of possible substrates.
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Jan 2016
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I19-Small Molecule Single Crystal Diffraction
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Michael L.
Baker
,
Tom
Lancaster
,
Alessandro
Chiesa
,
Giuseppe
Amoretti
,
Peter J.
Baker
,
Claire
Barker
,
Stephen J.
Blundell
,
Stefano
Carretta
,
David
Collison
,
Hans U.
Güdel
,
Tatiana
Guidi
,
Eric
Mcinnes
,
Johannes S.
Möller
,
Hannu
Mutka
,
Jacques
Ollivier
,
Francis L.
Pratt
,
Paolo
Santini
,
Floriana
Tuna
,
Philip L. W.
Tregenna-piggott
,
Inigo
Vitorica-yrezaba
,
Grigore A.
Timco
,
Richard E. P.
Winpenny
Open Access
Abstract: he spin dynamics of Cr8Mn, anine-memberedantiferromagn etic (AF) molecular nanomagnet, are investi-gated. Cr8Mn is arare exampleofalarge odd-membered AFring, and has an odd-numberof3d-electrons present. Od d-membered AF rings are unusualand of interest duetothepresence of competingexchange interactions that result infrustrated-spin ground states.The chemical synthesis andstructures of two Cr8Mn varian ts that differ only in their crys-tal packing are reported. Evidence of spin frustrationisin-vestigated by inelasticneutron scattering (INS) and muonspin relaxation spectroscopy (mSR). From INS studiesweac-curatelydetermine an appropriate microscopic spin Hamilto-nian and we showthat mSR is sensitive to the ground-spin-state crossing from S = 1/2 to S = 3/2 in Cr8Mn. The estimat-ed width of the muon asymmetry resonance is co nsisten twith the presence of an avoided crossing. The investigationof the internal spin structureofthe ground state, throughthe analysisofspin-pair correlations and scalar-spin chirality,showsanon-collinear spin structure that fluctuates betweennon-planar states of opposite chiralities.
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Jan 2016
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I19-Small Molecule Single Crystal Diffraction
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Jesús
Ferrando-soria
,
Eufemio
Moreno Pineda
,
Alessandro
Chiesa
,
Antonio
Fernandez Mato
,
Samantha A.
Magee
,
Stefano
Carretta
,
Paolo
Santini
,
Iñigo J.
Vitorica-yrezabal
,
Floriana
Tuna
,
Grigore A.
Timco
,
Eric
Mcinnes
,
Richard E.p.
Winpenny
Diamond Proposal Number(s):
[8977, 12745]
Open Access
Abstract: Quantum information processing (QIP) would require that the individual units involved—qubits—communicate to other qubits while retaining their identity. In many ways this resembles the way supramolecular chemistry brings together individual molecules into interlocked structures, where the assembly has one identity but where the individual components are still recognizable. Here a fully modular supramolecular strategy has been to link hybrid organic–inorganic [2]- and [3]-rotaxanes into still larger [4]-, [5]- and [7]-rotaxanes (Figure 1). The ring components are heterometallic octanuclear [Cr7NiF8(O2CtBu)16]– coordination cages and the thread components template the formation of the ring about the organic axle, and are further functionalized to act as a ligand, which leads to large supramolecular arrays of these heterometallic rings. As the rings have been proposed as qubits for QIP, the strategy provides a possible route towards scalable molecular electron spin devices for QIP. Double electron–electron resonance experiments demonstrate inter-qubit interactions suitable for mediating two-qubit quantum logic gates.
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Jan 2016
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I19-Small Molecule Single Crystal Diffraction
|
James P. S.
Walsh
,
Sarah B.
Meadows
,
Alberto
Ghirri
,
Fabrizio
Moro
,
Martin
Jennings
,
William F.
Smith
,
Darren M.
Graham
,
Takumi
Kihara
,
Hiroyuki
Nojiri
,
Inigo
Vitorica
,
Grigore A.
Timco
,
David
Collison
,
Eric
Mcinnes
,
Richard E. P.
Winpenny
Diamond Proposal Number(s):
[8977]
Abstract: A novel fluoride-centered carboxylate triangular-bridged complex, [Ni2Cr(μ3-F)(O2CtBu)6(HO2CtBu)3] (1), is reported. Simple post-synthetic substitution of the terminal pivalic acids in 1 with pyridine and 4-methylpyridine led to the isolation of [Ni2Cr(μ3-F)(O2CtBu)6(C5H5N)3] (2), and [Ni2Cr(μ3-F)(O2CtBu)6((4-CH3)C5H4N)3] (3). Structural and magnetic characterization carried out on the series revealed a dominating antiferromagnetic interaction between the nickel and chromium centres leading to an S = 1/2 ground state with a very unusual geff = 2.48.
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Dec 2015
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[7847]
Open Access
Abstract: Three complexes of cyclotricatechylene (H6ctc), [{PtL}3(m3-ctc)], have been synthesised: (L ¼ 1,2-bis(diphenylphosphino)benzene {dppb}, 1; L ¼ 1,2-bis(diphenylphosphino)ethane {dppe}, 2; L ¼ 4,40- bis(tert-butyl)-2,20-bipyridyl {tBu2bipy}, 3). The complexes show three low-potential, chemically reversible voltammetric oxidations separated by ca. 180 mV, corresponding to stepwise oxidation of the [ctc]6 catecholato rings to the semiquinonate level. The redox series [1]0/1+/2+/3+ and [3]0/1+/2+/3+ have been characterised by UV/vis/NIR spectroelectrochemistry. The mono- and di-cations have class II mixed valent character, with reduced radical delocalisation compared to an analogous bis-dioxolene ystem. The SOMO composition of [1c]+ and [3c]+ has been delineated by cw EPR, ENDOR and HYSCORE spectroscopies, with the aid of two monometallic model compounds [PtL(DBsqc)]+ (DBsqH ¼ 3,5-bis(tert-butyl)-1,2-benzosemiquinone; L ¼ dppe or tBu2bipy). DF and time-dependent DF calculations confirm these interpretations, and emonstrate changes to spin-delocalisation in the ctc macrocycle as it is sequentially oxidised.
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Aug 2015
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