Metallocene basicity

Bitterwolf, Thomas E.; Ling, A. Campbell

doi:10.1016/s0022-328x(00)89643-6

Cited by 44 publications

(20 citation statements)

References 3 publications

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“…[9,10] The mechanism of the catalysis involves simultaneous homolytic cleavage of transient FeÀH species during conformational flexing of the catalyst as shown in Scheme 1. [10] Theoretical calculations indicate that the bound H + ions in intermediate 2 are effectively atomic hydrogen (HC) with most of their positive charge resident on the metal.…”

Section: Nonbiological Homogeneous Catalystsmentioning

confidence: 99%

Homogeneous Catalysts with a Mechanical (“Machine‐like”) Action

Swiegers

Huang

Brimblecombe

et al. 2009

Chemistry A European J

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Chemical reactions may be controlled by either: 1) the minimum threshold energy that must be overcome during collisions between reactant molecules/atoms (the activation energy, E(a)), or: 2) the rate at which reactant collisions occur (the collision frequency, A)--for reactions with low E(a). Reactions of type 2 are governed by the physical, mechanical interaction of the reactants. Such mechanical processes are unusual, but not unknown in molecular catalysts. In this work we examine the machine-like nature of the action in various abiological mechanical catalysts and consider the implications for mimicry of biological catalysts.

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Section: Nonbiological Homogeneous Catalystsmentioning

confidence: 99%

Homogeneous Catalysts with a Mechanical (“Machine‐like”) Action

Swiegers

Huang

Brimblecombe

et al. 2009

Chemistry A European J

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“…The formation of complexes 3 ± 5 constitutes a rare example of the double protonation of a binuclear complex, especially considering the fact that the monohydride 2 is itself acidic. Previously reported double protonations in dirhodium complexes led to H 2 elimination [22] or to the formation of symmetric dihydrides similar to 6. [23] In addition, the double protonation of the complex [Cp*Ir(m-CO)] 2 has been reported to give a symmetric bis(hydrido)-bridged complex.…”

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confidence: 97%

Binuclear Oxidative Addition of Hydrogen in Diamidonaphthalene‐Bridged Diiridium Complexes

Jiménez

Sola

López

et al. 1998

Chemistry A European J

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) (7 a, 7 b), in which a molecule of hydrogen has been added to form a terminal and a bridging hydride. In the presence of NEt 3 , 7 a and 7 b isomerize into the symmetric complex 8 which presents a trans arrangement of the hydrides. Oxidation of complex 1 allows the preparation of the iridium(ii) species [Ir 2 (m-1,8-(NH) 2 naphth)(OSO 2 CF 3 ) 2 -(CO) 2 (PiPr 3 ) 2 ] (9). The triflate ligands of 9 can be replaced by tetrahydrothiophene or acetonitrile to give complexes 10 and 11, respectively. The acetonitrile complexes can exist as three different isomers: two have C 2 symmetry (11 a, 11 c) and one is asymmetric (11 b); the latter has been characterized by X-ray diffraction. The kinetic study of the isomerization reactions reveals these processes to be strictly intramolecular. The reaction of 9 with hydrogen gives different final products, depending on the solvent. Thus, in CDCl 3 the dihydride 3 is obtained, whereas in acetone a mixture of the trihydrides 7 a and 7 b is formed.

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“…An X-ray crystal structure, along with molecular modelling, showed the Fe … Fe distance in 15a to oscillate between 3.4 -4.8 Å during flexing [46]. H 2 formation by 15a therefore effectively involved the homolytic combination of two Fe-bound atomic hydrogen atoms during flexing (as illustrated in 18a (Figure 5)) [36,47,48].…”

Section: Tethered Ferrocene Catalystsmentioning

confidence: 99%

“…A wide range of mono-and di-ferrocene compounds have been prepared and studied, including 10-14 (Scheme 8) [36,37]. None of these species has ever been reported to display any sort of catalytic properties whatsoever.…”

Section: Tethered Ferrocene Catalystsmentioning

confidence: 99%

“…None of these species has ever been reported to display any sort of catalytic properties whatsoever. However, in 1973, Bitterwolf and Ling discovered that the di-ferrocene 15a (Scheme 9), which undergoes very rapid conformational flexing at room temperature, catalytically converted strong non-oxidizing acids to the dication 16a back to 15a to thereby close the catalytic cycle [36]. Further studies showed that the related ferrocenes and di-ferrocenes 10-13 did not catalyze the same transformation [38].…”

Section: Tethered Ferrocene Catalystsmentioning

confidence: 99%

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Kinematic molecular manufacturing machines

Boskovic

Balakrishnan

Huang

et al. 2016

Coordination Chemistry Reviews

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The principles of kinematic manufacturing machines of the type widely used since the industrial revolution are reviewed. Consideration is then given to how the principles of kinematics ('the geometry of motion') may manifest in molecular catalysts. Actions of this type involve synchronized, regular, repeated and rapid conformational flexing along geometrically optimum pathways that define a single degree of freedom. The proposition that many of the catalysts of biology, enzymes, may generally exploit a kinematic action is discussed. Thereafter, in the major portion of this work, representative abiological molecular catalysts whose actions display the characteristic features of kinematic manufacturing processes, are reviewed. In accordance with the principles of kinematics, molecular catalytic actions of this type are shown to be capable of transforming unremarkable chemical species into powerful catalysts with high activities, selectivities, and durabilities. Disciplines Engineering | Physical Sciences and Mathematics Engineering, Wenzhou University, Wenzhou 325027, Peoples Republic of ChinaAbstract: The principles of kinematic manufacturing machines of the type widely used since the industrial revolution are reviewed. Consideration is then given to how the principles of kinematics ('the geometry of motion') may manifest in molecular catalysts. Actions of this type involve synchronized, regular, repeated and rapid conformational flexing along geometrically optimum pathways that define a single degree of freedom. The proposition that many of the catalysts of biology, enzymes, may generally exploit a kinematic action is discussed. Thereafter, in the major portion of this work, representative abiological molecular catalysts whose actions display the characteristic features of kinematic manufacturing processes, are reviewed. In accordance with the principles of kinematics, molecular catalytic actions of this type are shown to be capable of transforming unremarkable chemical species into powerful catalysts with high activities, selectivities, and durabilities.

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Metallocene basicity

Cited by 44 publications

References 3 publications

Homogeneous Catalysts with a Mechanical (“Machine‐like”) Action

Homogeneous Catalysts with a Mechanical (“Machine‐like”) Action

Binuclear Oxidative Addition of Hydrogen in Diamidonaphthalene‐Bridged Diiridium Complexes

Kinematic molecular manufacturing machines

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