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Bennie SJ, Collison D, McDouall JJW. Electronic and Magnetic Properties of Kremer’s tris-Hydroxo Bridged Chromium Dimer: A Challenge for DFT. J Chem Theory Comput 2012; 8:4915-21. [DOI: 10.1021/ct300615w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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77
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Roberts HN, Brown NJ, Edge R, Fitzgerald EC, Ta YT, Collison D, Low PJ, Whiteley MW. Synthesis, Redox Chemistry, and Electronic Structure of the Butadiynyl and Hexatriynyl Complexes [Mo{(C≡C)nC≡CR}(L2)(η-C7H7)]z+ (n = 1, 2; z = 0, 1; R = SiMe3, H; L2 = 2,2′-bipyridine, Ph2PCH2CH2PPh2). Organometallics 2012. [DOI: 10.1021/om3005756] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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78
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Tuna F, Smith CA, Bodensteiner M, Ungur L, Chibotaru LF, McInnes EJL, Winpenny REP, Collison D, Layfield RA. A High Anisotropy Barrier in a Sulfur-Bridged Organodysprosium Single-Molecule Magnet. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202497] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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79
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Tuna F, Smith CA, Bodensteiner M, Ungur L, Chibotaru LF, McInnes EJL, Winpenny REP, Collison D, Layfield RA. A High Anisotropy Barrier in a Sulfur-Bridged Organodysprosium Single-Molecule Magnet. Angew Chem Int Ed Engl 2012; 51:6976-80. [DOI: 10.1002/anie.201202497] [Citation(s) in RCA: 239] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/09/2012] [Indexed: 11/10/2022]
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80
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Groarke JD, Buckley U, Collison D, O'Neill J, Mahon NG, Foley B. Cost implications of defibrillator lead failures. Europace 2012; 14:1156-60. [DOI: 10.1093/europace/eus006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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81
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Stephen E, Blake AJ, Carter E, Collison D, Davies ES, Edge R, Lewis W, Murphy DM, Wilson C, Gould RO, Holder AJ, McMaster J, Schröder M. Redox Non-innocence of Thioether Crowns: Elucidation of the Electronic Structure of the Mononuclear Pd(III) Complexes [Pd([9]aneS3)2]3+ and [Pd([18]aneS6)]3+. Inorg Chem 2012; 51:1450-61. [DOI: 10.1021/ic2017006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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82
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Callison J, Edge R, de Cuba KR, Carr RH, McDouall JJW, Collison D, McInnes EJL, van der Borden W, van der Velde K, Winfield JM, Lennon D. Origin of Impurities Formed in the Polyurethane Production Chain. 1. Conditions for Chlorine Transfer from an Aryl Isocyanide Dichloride Byproduct. Ind Eng Chem Res 2012. [DOI: 10.1021/ie2013136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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83
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Fitzgerald EC, Brown NJ, Edge R, Helliwell M, Roberts HN, Tuna F, Beeby A, Collison D, Low PJ, Whiteley MW. Orbital Symmetry Control of Electronic Coupling in a Symmetrical, All-Carbon-Bridged “Mixed Valence” Compound: Synthesis, Spectroscopy, and Electronic Structure of [{Mo(dppe)(η-C7H7)}2(μ-C4)]n+ (n = 0, 1, or 2). Organometallics 2011. [DOI: 10.1021/om200712m] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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84
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Murray PR, Collison D, Daff S, Austin N, Edge R, Flynn BW, Jack L, Leroux F, McInnes EJL, Murray AF, Sells D, Stevenson T, Wolowska J, Yellowlees LJ. An in situ electrochemical cell for Q- and W-band EPR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 213:206-209. [PMID: 22000629 DOI: 10.1016/j.jmr.2011.09.041] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 09/16/2011] [Accepted: 09/19/2011] [Indexed: 05/31/2023]
Abstract
A simple design for an in situ, three-electrode spectroelectrochemical cell is reported that can be used in commercial Q- and W-band (ca. 34 and 94 GHz, respectively) electron paramagnetic resonance (EPR) spectrometers, using standard sample tubing (1.0 and 0.5 mm inner diameter, respectively) and within variable temperature cryostat systems. The use of the cell is demonstrated by the in situ generation of organic free radicals (quinones and diimines) in fluid and frozen media, transition metal ion radical anions, and on the enzyme nitric oxide synthase reductase domain (NOSrd), in which a pair of flavin radicals are generated.
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Faust TB, Bellini V, Candini A, Carretta S, Lorusso G, Allan DR, Carthy L, Collison D, Docherty RJ, Kenyon J, Machin J, McInnes EJL, Muryn CA, Nowell H, Pritchard RG, Teat SJ, Timco GA, Tuna F, Whitehead GFS, Wernsdorfer W, Affronte M, Winpenny REP. Chemical Control of Spin Propagation between Heterometallic Rings. Chemistry 2011; 17:14020-30. [DOI: 10.1002/chem.201101785] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Indexed: 11/09/2022]
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86
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Stephen E, Huang D, Shaw JL, Blake AJ, Collison D, Davies ES, Edge R, Howard JAK, McInnes EJL, Wilson C, Wolowska J, McMaster J, Schröder M. Redox Non-Innocence of Thioether Crowns: Spectroelectrochemistry and Electronic Structure of Formal Nickel(III) Complexes of Aza-Thioether Macrocycles. Chemistry 2011; 17:10246-58. [DOI: 10.1002/chem.201100812] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Indexed: 11/06/2022]
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87
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Whalley AL, Blake AJ, Collison D, Davies ES, Disley HJ, Helliwell M, Mabbs FE, McMaster J, Wilson C, Garner CD. Synthesis, structure and redox properties of bis(cyclopentadienyl)dithiolene complexes of molybdenum and tungsten. Dalton Trans 2011; 40:10457-72. [PMID: 21785804 DOI: 10.1039/c1dt10663e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The compounds [Cp(2)M(S(2)C(2)(H)R)] (M = Mo or W; R = phenyl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl or quinoxalin-2-yl) and [Cp(2)Mo(S(2)C(2)(Me)(pyridin-2-yl)] have been prepared by a facile and general route for the synthesis of dithiolene complexes, viz. the reaction of [Cp(2)MCl(2)] (M = Mo or W) with the dithiolene pro-ligand generated by reacting the corresponding 4-(R)-1,3-dithiol-2-one with CsOH. These Mo compounds were reported previously (Hsu et al., Inorg. Chem. 1996, 35, 4743); however, the preparative method employed herein is more versatile and generates the compounds in good yield and all of the W compounds are new. Electrochemical investigations have shown that each compound undergoes a diffusion controlled one-electron oxidation (OX(I)) and a one-electron reduction (RED(I)) process; each redox change occurs at a more positive potential for a Mo compound than for its W counterpart. The mono-cations generated by chemical or electrochemical oxidation are stable and the structures of both components of the [Cp(2)Mo(S(2)C(2)(H)R)](+)/[Cp(2)Mo(S(2)C(2)(H)R)] (R = Ph or pyridin-3-yl) redox couples have been determined by X-ray crystallography. For each redox related pair, the changes in the Mo-S, S-C and C-C bond lengths of the {MoSCCS} moiety are generally consistent with OX(I) involving the loss of an electron from a π-orbital that is Mo-S and C-S antibonding and C-C bonding in character. These results have been interpreted successfully within the framework provided by DFT calculations accomplished for [Cp(2)M(S(2)C(2)(H)Ph)](n) (M = Mo or W; n = +1, 0 or -1). The HOMO of the neutral compounds is derived mainly from the dithiolene π(3) orbital (65%); therefore, OX(I) is essentially a dithiolene-based process. The similarity of the potentials for OX(I) (ca. 30 mV) for analogous Mo and W compounds is consistent with this interpretation and the EPR spectra of each of the Mo cations show that the unpaired electron is coupled to the dithiolene proton but relatively weakly to (95,97)Mo. The DFT calculations indicate that the unpaired electron is more localised on the metal in the mono-anions than in the mono-cations. In agreement with this, the EPR spectrum of each of the Mo-containing mono-anions manifests a larger (95,97)Mo coupling (A(iso)) than observed for the corresponding mono-cation and RED(I) for a W compound is significantly (ca. 300 mV) more negative than that of its Mo counterpart. [Cp(2)W(S(2)C(2)(H)(quinoxalin-2-yl))] is anomalous; RED(I) occurs at a potential ca. 230 mV more positive than expected from that of its Mo counterpart and the EPR spectrum of the mono-anion is typical of an organic radical. DFT calculations indicate that these properties arise because the electron is added to a quinoxalin-2-yl π-orbital.
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88
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Fitzgerald EC, Ladjarafi A, Brown NJ, Collison D, Costuas K, Edge R, Halet JF, Justaud F, Low PJ, Meghezzi H, Roisnel T, Whiteley MW, Lapinte C. Spectroscopic Evidence for Redox Isomerism in the 1,4-Diethynylbenzene-Bridged Heterobimetallic Cation [{Fe(dppe)Cp*}(μ-C≡CC6H4C≡C){Mo(dppe)(η-C7H7)}]PF6. Organometallics 2011. [DOI: 10.1021/om200488b] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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89
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Roberts (née Lancashire) HN, Brown NJ, Edge R, Lewin R, Collison D, Low PJ, Whiteley MW. Synthesis, Redox Chemistry, and Electronic Structure of the Alkynyl Cyclopentadienyl Molybdenum Complexes [Mo(C≡CR)(CO)(L2)Cp′]n+ (n = 0 or 1; R = Ph or C6H4-4-Me, L2 = Ph2PCH2CH2PPh2 or 2PMe3, Cp′ = Cp or Cp*). Organometallics 2011. [DOI: 10.1021/om200229c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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90
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Collins AM, Blanchard GJ, Hawkett J, Collison D, Marken F. Liquid|liquid|electrode triple-phase boundary photovoltammetry of pentoxyresorufin in 4-(3-phenylpropyl)pyridine. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:6471-6477. [PMID: 21488643 DOI: 10.1021/la2010584] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Voltammetric responses of pentoxyresorufin in 4-(3-phenylpropyl)-pyridine (PPP) microdroplets immersed in aqueous electrolyte are investigated in the absence and in the presence of light. The reduction of pentoxyresorufin to leuco-pentoxyresorufin in the dark is shown to occur in a two-electron, two-proton process sensitive to the aqueous pH and the PPP|aqueous electrolyte interfacial tension. No significant net photoelectrochemical current responses are observed, although transient responses indicative of distinct electron and hole charge carriers are seen in the presence of pentoxyresorufin. EPR evidence confirms the formation of radical intermediates upon illumination. As a coreactant, duroquinone in the PPP microdroplet phase is investigated and also shown to undergo two-electron, two-proton reduction (to duroquinol) without significant photoelectrochemical activity. When investigated in combination, pentoxyresorufin acts as a photocatalyst for the oxidation of duroquinol to duroquinone. Wavelength-resolved photovoltammetry experiments clearly implicate pentoxyresorufin as the primary photoexcited intermediate. The photoelectrochemical mechanism is explained on the basis of the presence of a long-lived (possibly charge-separated) photoexcited intermediate in the PPP microphase. Implications for light-energy harvesting are discussed.
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91
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Collison D. Magnetic Resonance in Chemistry. Editorial. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2011; 49:151. [PMID: 21437980 DOI: 10.1002/mrc.2759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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92
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Boeer AB, Barra AL, Chibotaru LF, Collison D, McInnes EJL, Mole RA, Simeoni GG, Timco GA, Ungur L, Unruh T, Winpenny REP. A Spectroscopic Investigation of Magnetic Exchange Between Highly Anisotropic Spin Centers. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201100306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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93
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Boeer AB, Barra AL, Chibotaru LF, Collison D, McInnes EJL, Mole RA, Simeoni GG, Timco GA, Ungur L, Unruh T, Winpenny REP. A Spectroscopic Investigation of Magnetic Exchange Between Highly Anisotropic Spin Centers. Angew Chem Int Ed Engl 2011; 50:4007-11. [DOI: 10.1002/anie.201100306] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Indexed: 11/10/2022]
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94
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Sulway SA, Collison D, McDouall JJW, Tuna F, Layfield RA. Iron(II) Cage Complexes of N-Heterocyclic Amide and Bis(trimethylsilyl)amide Ligands: Synthesis, Structure, and Magnetic Properties. Inorg Chem 2011; 50:2521-6. [DOI: 10.1021/ic102341a] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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95
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Baker ML, Bianchi A, Carretta S, Collison D, Docherty RJ, McLnnes EJL, McRobbie A, Muryn CA, Mutka H, Piligkos S, Rancan M, Santini P, Timco GA, Tregenna-Piggott PLW, Tuna F, Güdel HU, Winpenny REP. Varying spin state composition by the choice of capping ligand in a family of molecular chains: detailed analysis of magnetic properties of chromium(III) horseshoes. Dalton Trans 2011; 40:2725-34. [PMID: 21311776 DOI: 10.1039/c0dt01243b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a detailed physical analysis on a family of isolated, antiferro-magnetically (AF) coupled, chromium(III) finite chains, of general formula (Cr(RCO(2))(2)F)(n) where the chain length n = 6 or 7. Additionally, the chains are capped with a selection of possible terminating ligands, including hfac (= l,l,l,5,5,5-hexafluoropentane-2,4-dionate(l-)), acac (= pentane-2,4-dionate(l-)) or (F)(3). Measurements by inelastic neutron scattering (INS), magnetometery and electron paramagnetic resonance (EPR) spectroscopy have been used to study how the electronic properties are affected by n and capping ligand type. These comparisons allowed the subtle electronic effects the choice of capping ligand makes for odd member spin 3/2 ground state and even membered spin 0 ground state chains to be investigated. For this investigation full characterisation of physical properties have been performed with spin Hamiltonian parameterisation, including the determination of Heisenberg exchange coupling constants and single ion axial and rhombic anisotropy. We reveal how the quantum spin energy levels of odd or even membered chains can be modified by the type of capping ligand terminating the chain. Choice of capping ligands enables Cr-Cr exchange coupling to be adjusted by 0, 4 or 24%, relative to Cr-Cr exchange coupling within the body of the chain, by the substitution of hfac, acac or (F)(3) capping ligands to the ends of the chain, respectively. The manipulation of quantum spin levels via ligands which play no role in super-exchange, is of general interest to the practise of spin Hamilton modelling, where such second order effects are generally not considered of relevance to magnetic properties.
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96
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Ferguson J, Collison D, Power D, Stevenson L. Accounting education, socialisation and the ethics of business. ACTA ACUST UNITED AC 2011. [DOI: 10.1111/j.1467-8608.2010.01607.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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97
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Baker ML, Piligkos S, Bianchi A, Carretta S, Collison D, McDouall JJW, McInnes EJL, Mutka H, Timco GA, Tuna F, Vadivelu P, Weihe H, Güdel HU, Winpenny REP. Modification of the magnetic properties of a heterometallic wheel by inclusion of a Jahn–Teller distorted Cu(ii) ion. Dalton Trans 2011; 40:8533-9. [DOI: 10.1039/c1dt10547g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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98
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Redmond MP, Cornet SM, Woodall SD, Whittaker D, Collison D, Helliwell M, Natrajan LS. Probing the local coordination environment and nuclearity of uranyl(vi) complexes in non-aqueous media by emission spectroscopy. Dalton Trans 2011; 40:3914-26. [DOI: 10.1039/c0dt01464h] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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99
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Lancashire HN, Brown NJ, Carthy L, Collison D, Fitzgerald EC, Edge R, Helliwell M, Holden M, Low PJ, McDouall JJW, Whiteley MW. Synthesis, spectroscopy and electronic structure of the vinylidene and alkynyl complexes [W(CCHR)(dppe)(η-C7H7)]+and [W(CCR)(dppe)(η-C7H7)]n+(n = 0 or 1). Dalton Trans 2011; 40:1267-78. [DOI: 10.1039/c0dt01150a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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100
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Sharples JW, Zheng YZ, Tuna F, McInnes EJL, Collison D. Lanthanide discs chill well and relax slowly. Chem Commun (Camb) 2011; 47:7650-2. [DOI: 10.1039/c1cc12252e] [Citation(s) in RCA: 238] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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