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F. Geoffrey N. Cloke

Bio: F. Geoffrey N. Cloke is an academic researcher from University of Sussex. The author has contributed to research in topics: Pentalene & Carbene. The author has an hindex of 42, co-authored 178 publications receiving 5979 citations. Previous affiliations of F. Geoffrey N. Cloke include University College London & Russian Academy of Sciences.


Papers
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Journal ArticleDOI
10 Feb 2006-Science
TL;DR: It is found that an organouranium(III) complex induces efficient reductive trimerization of carbon monoxide at room temperature and pressure to form a triangular, cyclic C3O 2–3, or deltate, dianion held between two uranium(IV) units.
Abstract: Despite the long history of the Fischer-Tropsch reaction, carbon monoxide has proven remarkably resistant to selective homologation under mild conditions. Here, we find that an organouranium(III) complex induces efficient reductive trimerization of carbon monoxide at room temperature and pressure. The result is a triangular, cyclic C3O32-, or deltate, dianion held between two uranium(IV) units. The bonding within the C 3O32- unit and its coordination to the two U centers have been analyzed by x-ray diffraction and density functional theory computational studies, which show a stabilizing C-C agostic interaction between the C3 core and one U center. Solution nuclear magnetic resonance studies reveal a rapid equilibration of the deltate unit between the U centers.

249 citations

Journal ArticleDOI
TL;DR: The reaction between [Ni(1,5-cod)2] (cod=cyclooctadiene) and 1,3-bis-tert-butylimidazol-2-ylidene in the presence of silicone grease affords the siloxane bridged dimer 2, and in a greaseless apparatus the same reaction yields the dimer 1, via two structurally characterized intermediates.
Abstract: Reaction lubrication? The reaction between [Ni(1,5-cod)2] (cod=cyclooctadiene) and 1,3-bis-tert-butylimidazol-2-ylidene in the presence of silicone grease affords the siloxane bridged dimer [{Ni[C(NtBuCH) 2][O(Me2SiOSiMe2)-µ-O]}2]. In a greaseless apparatus, the same reaction yields the dimer 1 (see structure), via two structurally characterized intermediates.

153 citations

Journal ArticleDOI
TL;DR: The U(III) mixed-sandwich compound may be prepared by sequential reaction of UI(3) with KCp followed by K(2)[C(8)H(4)[Si(i)Pr(3)-1,4](2)], and has been crystallographically characterized.
Abstract: The U(III) mixed-sandwich compound [U(?-Cp*)(?-C8H4{SiiPr3-1,4}2)] 1 may be prepared by sequential reaction of UI3 with KCp* followed by K2[C8H4{SiiPr3-1,4}2], and has been crystallographically characterized. 1 reacts reversibly with dinitrogen to afford dimeric [{U(?-Cp*)(?-C8H4{SiiPr3-1,4}2)}2(µ-?2:?2-N2)] 2 , whose X-ray crystal structure reveals a sideways-bound, bridging diazenido (N22-) ligand. Copyright © 2002 American Chemical Society.

152 citations

Journal ArticleDOI
TL;DR: Spectroscopic and computational studies suggest a plausible mechanism for the formation of the deltate complex, in which a "zig-zag" diuranium ynediolate species is the key intermediate.
Abstract: The stoichiometric reaction of 1 equiv of CO with [(U(eta-C8H6{SiiPr3-1,4}2)(eta-Cp*)] affords the linear diuranium ynediolate complex [(U(eta-C8H6{SiiPr3-1,4}2)(eta-Cp*)]2(mu-eta1:eta1-C2O2) which does not react with further CO to give the deltate derivative [(U(eta-C8H6{SiiPr3-1,4}2)(eta-Cp*)]2(mu-eta1:eta2-C3O3). Spectroscopic and computational studies suggest a plausible mechanism for the formation of the deltate complex, in which a "zig-zag" diuranium ynediolate species is the key intermediate.

139 citations


Cited by
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Journal ArticleDOI
10 Mar 1970

8,159 citations

Journal ArticleDOI
TL;DR: 1. Advantages and disadvantages of Chemical Redox Agents, 2. Reversible vs Irreversible ET Reagents, 3. Categorization of Reagent Strength.
Abstract: 1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 1. Radical Cations 891 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich Compounds 894

3,432 citations

Journal ArticleDOI
TL;DR: N-Heterocyclic carbenes have become universal ligands in organometallic and inorganic coordination chemistry as mentioned in this paper, and they not only bind to any transition metal, be it in low or high oxidation states, but also to main group elements such as beryllium, sulfur, and iodine.
Abstract: N-Heterocyclic carbenes have become universal ligands in organometallic and inorganic coordination chemistry. They not only bind to any transition metal, be it in low or high oxidation states, but also to main group elements such as beryllium, sulfur, and iodine. Because of their specific coordination chemistry, N-heterocyclic carbenes both stabilize and activate metal centers in quite different key catalytic steps of organic syntheses, for example, C-H activation, C-C, C-H, C-O, and C-N bond formation. There is now ample evidence that in the new generation of organometallic catalysts the established ligand class of organophosphanes will be supplemented and, in part, replaced by N-heterocyclic carbenes. Over the past few years, this chemistry has been the field of vivid scientific competition, and yielded previously unexpected successes in key areas of homogeneous catalysis. From the work in numerous academic laboratories and in industry, a revolutionary turning point in oraganometallic catalysis is emerging.

3,388 citations

Journal ArticleDOI
TL;DR: This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.
Abstract: Although fire is now rarely used in synthetic chemistry, it was not until Robert Bunsen invented the burner in 1855 that the energy from this heat source could be applied to a reaction vessel in a focused manner. The Bunsen burner was later superseded by the isomantle, oil bath, or hot plate as a source for applying heat to a chemical reaction. In the past few years, heating and driving chemical reactions by microwave energy has been an increasingly popular theme in the scientific community. This nonclassical heating technique is slowly moving from a laboratory curiosity to an established technique that is heavily used in both academia and industry. The efficiency of "microwave flash heating" in dramatically reducing reaction times (from days and hours to minutes and seconds) is just one of the many advantages. This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.

3,044 citations