Structure−Activity Correlation in Titanium Single-Site Olefin Polymerization Catalysts Containing Mixed Cyclopentadienyl/Aryloxide Ligation

Manz, Thomas A.; Phomphrai, Khamphee; Medvedev, Grigori A.; Krishnamurthy, Balachandra; Sharma, Shalini; Haq, Jesmin; Novstrup, Krista A.; Thomson, Kendall T.; Delgass, W. Nicholas; Caruthers, James M.; Abu‐Omar, Mahdi M.

doi:10.1021/ja0640849

Cited by 52 publications

(68 citation statements)

References 8 publications

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“…[62][63][64] Since the catalysts studied here do not involve ions, the relative importance of solvation effects will be smaller. The zero-point energy (E zp ), enthalpy (H, at standard condition), and Gibbs free energy (G, at standard condition) for all geometries we studied are reported in the ESI.…”

Section: Methodsmentioning

confidence: 99%

Hafnium catalysts for direct alkene epoxidation using molecular oxygen as oxidant

Manz

2015

RSC Adv.

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New zirconium (Zr) based organometallic catalysts for direct olefin epoxidation using O 2 as oxidant without coreductant were introduced in a previous computational study (T. A. Manz and B. Yang, RSC Adv., 2014, 4, 27755-27774). In this paper, we use density functional theory (DFT) to study three Hf-based catalysts with the same bis(bidentate) ligands as the preceding Zr-based catalysts: (a) the diimine ligand N(Ar)-CH-CH-N(Ar) aka NCCN, (b) the imine-nitrone ligand N(Ar)-CH-CH-N(Ar)-O aka NCCNO, and (c) the dinitrone ligand O-N(Ar)-CH-CH-N(Ar)-O aka ONCCNO [Ar ¼ -C 6 H 3 -2,6-i Pr 2 ]. Complete reaction cycles and energetic spans (i.e., effective activation energies for the entire catalytic cycle) are computed for propene epoxidation. For Hf_NCCNO and Hf_ONCCNO, the reaction cycles are similar to the Zr-basedanalogs and the formation of h 3 -ozone intermediates is still crucial. Hf_ONCCNO has a large enthalpic energetic span (60.4 kcal mol À1 ) due to forming inert octahedral complexes as the catalyst resting state.Our calculations predict an energetic span $40 kcal mol À1 for Hf_NCCN, which indicates it will not be a good catalyst. Computed enthalpic energetic spans of $30 kcal mol À1 are achieved for the Hf_NCCNO and Zr_NCCNO catalysts; however, transfer of allylic hydrogen from the reaction product forms a low energy deactivation product. Therefore, the Hf_NCCNO and Zr_NCCNO catalysts are only suitable for direct epoxidation of alkenes that do not have any allylic hydrogen atoms. As an example of an alkene with no allylic hydrogens, we computed enthalpic energetic spans (kcal mol À1 ) for direct ethylene epoxidation of (a) 25.0 for Hf_NCCNO, (b) 30.2 for Zr_NCCNO, and (c) 52.7 for Zr_NCCN. † Electronic supplementary information (ESI) available: DFT-optimized geometries and energies; imaginary frequency for each transition state; singlet-triplet crossing curves for O 2 addition to Hf_ONCCNO and Hf_NCCN dioxo complexes; constrained optimization curves showing oxo h 3 -ozone and peroxo h 3 -ozone complexes do not exist for the Hf_NCCN system; chemical potential diagrams for Hf_ONCCNO and Hf_NCCN; assigned spin magnetic moments tables; master cycle and table of reaction energies and energetic spans for direct propene epoxidation catalyzed by Hf_ONCCNO; master cycles and tables of reaction energies and energetic spans for direct ethylene epoxidation catalyzed by Zr_NCCN, Hf_NCCNO, and Zr_NCCNO. See

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Section: Methodsmentioning

confidence: 99%

Hafnium catalysts for direct alkene epoxidation using molecular oxygen as oxidant

Manz

2015

RSC Adv.

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“…Titanium containing materials have attracted attention in catalysis, solar cells, gas sensors, and semiconductors in recent decades 15–19. For example, there is a great interest in titanium containing zeolite catalysts for selective oxidation recently.…”

Section: Introductionmentioning

confidence: 99%

Titanium Containing γ‐MnO₂ (TM) Hollow Spheres: One‐Step Synthesis and Catalytic Activities in Li/Air Batteries and Oxidative Chemical Reactions

Liu

Morein

et al. 2010

Adv Funct Materials

152

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Titanium containing γ -MnO 2 octahedral molecular sieves having hollow sphere structures are successfully prepared for the fi rst time using a one-step synthesis method. Titanium cations are used as structure-directing agents in the synthesis process. The assembly of the hollow spheres is carried out at the beginning of the process. Various techniques including XRD, N 2 adsorption, SEM, EDX, RAMAN, TEM, XPS, and TGA are employed for the materials characterization. Ti is incorporated into the MnO 2 framework in isolated sites, and TiO 2 phases (anatase and rutile) are not observed. When introduced in medium-sized lithium-air batteries, the materials give very high specifi c capacity (up to 2.3 A h g − 1 ). These materials are also catalytically tested in the oxidation of toluene with molecular oxygen at atmospheric pressure, showing signifi cant oxidative catalytic activities in this diffi cult chemical reaction.

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“…In particular, a dataset (DS-4) was made out of 22 contact ion pairs representing candidate active species in titanium-catalysed olefin polymerization (Figure 18). [189][190][191][192][193] The challenge introduced by these compounds is the proper handling of the relative position of the two ions. In this context, the combination of graph representation and 3D building blocks allowed to define the ionic interaction as a connection between two fragments and thus to treat the relative position of the two ions as any other couple of fragments.…”

Section: Case Studymentioning

confidence: 99%

Automated Design of Realistic Organometallic Molecules from Fragments

Foscato

Occhipinti

Venkatraman

et al. 2014

J. Chem. Inf. Model.

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A method for the automated generation of realistic, synthetically accessible transition metal and organometallic complexes is described. Computational tools were designed to generate molecular fragments, preferably harvested from libraries of existing, stable compounds, to be used as building blocks for the construction of new molecules. These fragments are enriched with information about the number and type of possible connections to other fragments and are stored in library files. When connecting fragments in the subsequent building process, compatibility matrices, which define the connection rules between fragments, are used to delineate organometallic fragment spaces from which molecules can be generated in an automated fashion. The approach is flexible and allows ample structural variation at the same time as the combination of known fragments is easily restrained to avoid generation of exotic and unrealistic substructures and molecules. The method was tested in the generation of ruthenium complexes, with a given coordination environment, which can serve as candidates in catalyst development. The results demonstrate that molecules generated with the described method do not contain exotic arrangements of atoms and are by far more realistic than those obtained by the application of valence rules alone.

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Structure−Activity Correlation in Titanium Single-Site Olefin Polymerization Catalysts Containing Mixed Cyclopentadienyl/Aryloxide Ligation

Cited by 52 publications

References 8 publications

Hafnium catalysts for direct alkene epoxidation using molecular oxygen as oxidant

Hafnium catalysts for direct alkene epoxidation using molecular oxygen as oxidant

Titanium Containing γ‐MnO₂ (TM) Hollow Spheres: One‐Step Synthesis and Catalytic Activities in Li/Air Batteries and Oxidative Chemical Reactions

Automated Design of Realistic Organometallic Molecules from Fragments

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Structure−Activity Correlation in Titanium Single-Site Olefin Polymerization Catalysts Containing Mixed Cyclopentadienyl/Aryloxide Ligation

Cited by 52 publications

References 8 publications

Hafnium catalysts for direct alkene epoxidation using molecular oxygen as oxidant

Hafnium catalysts for direct alkene epoxidation using molecular oxygen as oxidant

Titanium Containing γ‐MnO2 (TM) Hollow Spheres: One‐Step Synthesis and Catalytic Activities in Li/Air Batteries and Oxidative Chemical Reactions

Automated Design of Realistic Organometallic Molecules from Fragments

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Product

Resources

About

Titanium Containing γ‐MnO₂ (TM) Hollow Spheres: One‐Step Synthesis and Catalytic Activities in Li/Air Batteries and Oxidative Chemical Reactions