F. Gordon A. Stone

Bio: F. Gordon A. Stone is an academic researcher from University of Bristol. The author has contributed to research in topics: Carbyne & Cyclopentadienyl complex. The author has an hindex of 32, co-authored 418 publications receiving 8243 citations.

Metall‐Kohlenstoff‐ und Metall‐Metall‐Mehrfachbindungen als Liganden in der Übergangsmetallchemie: Die Isolobal‐Beziehung

Abstract: Als Folge der Erkenntnis, das Metall-Kohlenstoff- und Metall-Metall-Mehrfachbindungen in niedervalenten Ubergangsmetallkomplexen reaktive Zentren zur Anlagerung von Metall-Ligand-Fragmenten sein konnen, hat sich ein neues Synthesegebiet entwickelt. Die Produkte konnen sowohl homo- als auch heteronucleare Metall-Metall-Bindungen enthalten. Mit bruckenbildenden Kohlenstoffatomen entstehen Dimetallacyclopropan- oder -cyclopropen-Strukturen, deren organische Komponenten (Alkyliden- oder Alkylidingruppen) ein weitgefachertes Reaktionsverhalten zeigen. Das von Hoffmann et al. entwickelte isolobale Modell, das eine Beziehung zwischen den Grenzorbitalen organischer Gruppen und denen von Metall-Ligand-Fragmenten herstellt, ist zu einer erfolgversprechenden Leitlinie fur praparatives Arbeiten geworden.

Synthesis of ethylene, cyclo-octa-1,5-diene, bicyclo[2.2.1]heptene, and trans-cyclo-octene complexes of palladium(0) and platinum(0); crystal and molecular structure of tris(bicyclo[2.2.1]heptene)platinum

Abstract: Reaction of [Pt(1,5-C8H12)Cl2] with Li2(C8H8) in diethyl ether in the presence of excess of 1,5-C8H12 gives the white crystalline complex [Pt(1,5-C8H12)2] in good yield. A similar reaction of [Pd(1,5-C8H12)Cl2] in the presence of propene affords [Pd(1.5-C8H12)2]. stable below ambient temperatures. The reaction of [M(1,5-C8H12)Cl2](M = Pd or Pt) with Li2(C8H8) and excess of bicyclo[2.2.1]heptene gives, respectively, tris(bicyclo[2.2.1]heptene)- palladium and -platinum. These complexes are also obtained by displacement of cyclo-octa-1,5-diene from [M(1,5-C8H12)2](M = Pd or Pt) by bicyclo[2.2.1]heptene. Related displacement reactions with trans-cyclo-octene and ethylene afford, respectively, tris(trans-cyclo-octene)palladium, tris(trans-cyclo-octene)platinum. tris(ethylene)palladium, and tris(ethylene)platinum. The ethylene complexes are highly volatile, and can be isolated as crystalline species, although they readily deposit the metals. The structural identity of tris(bicyclo-[2.2.1]heptene)platinum has been established by analysis of single-crystal X-ray data recorded on a four-circle diffractometer both at room temperature and at 190 K. The complex is orthorhombic, space group P212121. Z= 4, a= 5.717(1), b= 10.735(4), c= 28.749(12)A, at 300 K: at 190 K a= 5.598(6), b= 10.775(16), c= 28.562(40)A. Full-matrix least-squares refinement, using 1 781 reflections, has converged to R 0.056 (R′ 0.066)(190 K data). The molecule has a trigonal-planar structure in which the maximum deviation from planarity is 0.03 A.

Comprehensive organometallic chemistry II : a review of the literature 1982-1994

Abstract: This is the only volume to provide a complete (1927 to date) coverage of this topic, being a listing (in convenient multi-tabular form) of structures of organometallic compounds determined by electron, neutron and x-ray diffraction methods. About 35,000 structures will be listed with relevant citations, which include those appearing up to mid-1993. This listing contains not only those which appear in the well-known Cambridge Crystallographic Data Base (CCDB), but also those which for some reason do not merit inclusion in the CCDB or only been illustrated in publications, without the crystallographic details. 'Metals' include all those whose chemistry is covered in the other volumes of "COMC II".

Catalytic Carbophilic Activation: Catalysis by Platinum and Gold π Acids

Abstract: The ability of platinum and gold catalysts to effect powerful atom-economic transformations has led to a marked increase in their utilization. The quite remarkable correlation of their catalytic behavior with the available structural data, coordination chemistry, and organometallic reactivity patterns, including relativistic effects, allows the underlying principles of catalytic carbophilic activation by π acids to be formulated. The spectrum of reactivity extends beyond their utility as catalytic and benign alternatives to conventional stoichiometric π acids. The resulting reactivity profile allows this entire field of catalysis to be rationalized, and brings together the apparently disparate electrophilic metal carbene and nonclassical carbocation explanations. The advances in coupling, cycloisomerization, and structural reorganization—from the design of new transformations to the improvement to known reactions—are highlighted in this Review. The application of platinum- and gold-catalyzed transformations in natural product synthesis is also discussed.

C-H Bond Functionalization in Complex Organic Synthesis

Abstract: Direct and selective replacement of carbon-hydrogen bonds with new bonds (such as C-C, C-O, and C-N) represents an important and long-standing goal in chemistry. These transformations have broad potential in synthesis because C-H bonds are ubiquitous in organic substances. At the same time, achieving selectivity among many different C-H bonds remains a challenge. Here, we focus on the functionalization of C-H bonds in complex organic substrates catalyzed by transition metal catalysts. We outline the key concepts and approaches aimed at achieving selectivity in complex settings and discuss the impact these reactions have on synthetic planning and strategy in organic synthesis.

ONIOM: A Multilayered Integrated MO + MM Method for Geometry Optimizations and Single Point Energy Predictions. A Test for Diels−Alder Reactions and Pt(P(t-Bu)3)2 + H2 Oxidative Addition

Abstract: The new ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) approach has been proposed and shown to be successful in reproducing benchmark calculations and experimental results. ONIOM3, a three-layered version, divides a system into an active part treated at a very high level of ab initio molecular orbital theory like CCSD(T), a semiactive part that includes important electronic contributions and is treated at the HF or MP2 level, and a nonactive part that is handled using force field approaches. The three-layered scheme allows us to study a larger system more accurately than the previously proposed two-layered schemes IMOMO, which can treat a medium size system very accurately, and IMOMM, which can handle a very large system with modest accuracy. This three-layered scheme has been applied to activation barriers for the Diels−Alder reaction of acrolein + isoprene, acrolein + 2-tert-butyl-1,3-butadiene, and ethylene + 1,4-di-tert-butyl-1,3-butadiene. In general, the results for b...

Cascade reactions in total synthesis.

Abstract: The design and implementation of cascade reactions is a challenging facet of organic chemistry, yet one that can impart striking novelty, elegance, and efficiency to synthetic strategies. The application of cascade reactions to natural products synthesis represents a particularly demanding task, but the results can be both stunning and instructive. This Review highlights selected examples of cascade reactions in total synthesis, with particular emphasis on recent applications therein. The examples discussed herein illustrate the power of these processes in the construction of complex molecules and underscore their future potential in chemical synthesis.

Asymmetric Catalysis by Architectural and Functional Molecular Engineering: Practical Chemo‐ and Stereoselective Hydrogenation of Ketones

Abstract: Hydrogenation is a core technology in chemical synthesis. High rates and selectivities are attainable only by the coordination of structurally well-designed catalysts and suitable reaction conditions. The newly devised [RuCl(2)(phosphane)(2)(1,2-diamine)] complexes are excellent precatalysts for homogeneous hydrogenation of simple ketones which lack any functionality capable of interacting with the metal center. This catalyst system allows for the preferential reduction of a C=O function over a coexisting C=C linkage in a 2-propanol solution containing an alkaline base. The hydrogenation tolerates many substituents including F, Cl, Br, I, CF(3), OCH(3), OCH(2)C(6)H(5), COOCH(CH(3))(2), NO(2), NH(2), and NRCOR as well as various electron-rich and -deficient heterocycles. Furthermore, stereoselectivity is easily controlled by the electronic and steric properties (bulkiness and chirality) of the ligands as well as the reaction conditions. Diastereoselectivities observed in the catalytic hydrogenation of cyclic and acyclic ketones with the standard triphenylphosphane/ethylenediamine combination compare well with the best conventional hydride reductions. The use of appropriate chiral diphosphanes, particularly BINAP compounds, and chiral diamines results in rapid and productive asymmetric hydrogenation of a range of aromatic and heteroaromatic ketones and gives a consistently high enantioselectivity. Certain amino and alkoxy ketones can be used as substrates. Cyclic and acyclic alpha,beta-unsaturated ketones can be converted into chiral allyl alcohols of high enantiomeric purity. Hydrogenation of configurationally labile ketones allows for the dynamic kinetic discrimination of diastereomers, epimers, and enantiomers. This new method shows promise in the practical synthesis of a wide variety of chiral alcohols from achiral and chiral ketone substrates. Its versatility is manifested by the asymmetric synthesis of some biologically significant chiral compounds. The high rate and carbonyl selectivity are based on nonclassical metal-ligand bifunctional catalysis involving an 18-electron amino ruthenium hydride complex and a 16-electron amido ruthenium species.