Raquel Gracia

The University of Sheffield, Sheffield, England, United Kingdom

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Publications (4)11.74 Total impact

  • Raquel Gracia · Nathan J Patmore
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    ABSTRACT: The preparation of Os2(TiPB)4Cl2 (; TiPB = 2,4,6-triisopropylbenzoate) and Os2(TiPB)2(OAc)2Cl2 () by carboxylate exchange reactions with Os2(OAc)4Cl2 is reported. The structure of has been determined by single-crystal X-ray studies, and shows a paddlewheel arrangement of the ligands about the triply bonded diosmium core. Both compounds have magnetic moments at room temperature that are consistent with the presence of two unpaired electrons, and their cyclic voltammograms show a single redox process corresponding to the Os2(5+/6+) redox couple. The electronic absorption spectra of and display an absorption at ∼395 nm, corresponding to the π(Cl) → π*(Os2) LMCT transition, as well as numerous weaker absorptions at lower energy. Density functional theory (DFT) calculations on Os2(OAc)4Cl2 at different levels of theory (B3LYP and PBE0) have been used to probe the electronic structure of diosmium tetracarboxylates. The calculations show that these compounds have a σ(2)π(4)δ(2)δ*(1)π*(1) electronic configuration, and time-dependent DFT was used to help rationalize their optical properties.
    No preview · Article · Jul 2013 · Dalton Transactions
  • Raquel Gracia · Harry Adams · Nathan J. Patmore
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    ABSTRACT: A series of Ru2II,III complexes containing the bulky carboxylate ligand 2,4,6-triisopropylbenzoate (TiPB) of type trans-[Ru2(TiPB)2(O2CCH3)2X] [X=Cl (1), PF6 (2)] and [Ru2(TiPB)4X] [X=Cl (3), PF6 (4)] have been synthesised. The corresponding Ru2II,II complexes trans-[Ru2(TiPB)2(O2CCH3)2] (5) and [Ru2(TiPB)4] (6) were also isolated. Magnetic susceptibility measurements indicate that the diruthenium cores have the expected three (1–4) or two (5 and 6) unpaired electrons consistent with σ2π4δ2(δ∗π∗)3 and σ2π4δ2δ∗2π∗2 electronic configurations. Compounds 1–4 and 6 were structurally characterised by X-ray crystallography, and show the expected paddlewheel arrangement of carboxylate ligands around the diruthenium core. The diruthenium cores of complexes 3, 4 and 6 are all distorted to minimise steric interactions between the bulky carboxylate ligands. The Ru–Ru bond length in the Ru2II,II complex 6 [2.2425(6)Å] is the shortest observed for a diruthenium tetracarboxylate and, surprisingly, is 0.014Å shorter than in the analogous Ru2II,III complex 4, despite an increase in the formal Ru–Ru bond order from 2.0 (6) to 2.5 (4). This is rationalised in terms of the extent of internal rotation, or distortion, about the diruthenium core. This was supported by density functional theory calculations on the model complexes [Ru2(O2CH)4] and [Ru2(O2CH)4]+, that demonstrate the relationship between Ru–Ru bond length and internal rotation. Electrochemical and electronic absorption data were recorded for all complexes in solution. Comparison of the data for the ‘bis–bis’ (1, 2 and 5) and tetra-substituted (3, 4 and 6) complexes indicates that the shortening of the Ru–Ru bond length results in a small increase in energy of the near-degenerate δ∗ and π∗ orbitals.
    No preview · Article · Nov 2010 · Inorganica Chimica Acta
  • Raquel Gracia · Nathan J. Patmore
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    ABSTRACT: The mixed carboxylate diruthenium complexes trans-[Ru2II,III(O2CCH3)2(O2CAr)2Cl] (I) and trans-[Ru2II,II(O2CCH3)2(O2CAr)2] (II) (O2CAr=2,6-di(p-tolyl)benzoate) have been synthesised along with [Ru2II,III(O2CAr)4Cl] (III) and the homoleptic complex [Ru2II,II(O2CAr)4] (IV). The structures trans-[Ru2(O2CCH3)2(O2CAr)2Cl(thf)]·(thf) and [Ru2(O2CAr)4Cl(η 1-CH2Cl2)] were determined by X-ray crystallography, and display the expected paddlewheel arrangement of the carboxylate ligands around the diruthenium core. The structure of III is a rare example of a structurally characterised dichloromethane complex, highlighting the Lewis acidic nature of the diruthenium axial position. The bulky −O2CAr ligand protects the axial positions from intermolecular interactions in the absence of strong nucleophiles for III and IV, and the effect this has on the electronic structure of the diruthenium core in these complexes was investigated by cyclic voltammetry, electronic absorption spectroscopy and magnetic susceptibility studies. KeywordsRuthenium-Metal–metal interactions-Carboxylate ligands
    No preview · Article · Sep 2010 · Journal of Cluster Science
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    Raquel Gracia · Harry Adams · Nathan J Patmore
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    ABSTRACT: The Ru-Ru bond length for Ru2II,III and Ru2II,II paddlewheel complexes containing the bulky carboxylate ligand 2,4,6-triisopropylbenzoate was found to decrease despite a reduction in Ru-Ru bond order, due to increased internal rotation.
    Preview · Article · Feb 2009 · Dalton Transactions

Publication Stats

14 Citations
11.74 Total Impact Points


  • 2009-2013
    • The University of Sheffield
      • Department of Chemistry
      Sheffield, England, United Kingdom