π–π Interaction Directed Applications of Metal Complexes

Sutradhar, Manas; Pombeiro, Armando J. L.

doi:10.1002/9781119113874.ch6

Cited by 3 publications

(3 citation statements)

References 72 publications

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“…One prominent feature that has been observed in Ti1 is that the phenyl group on the dibenzhydryl moiety can form π-π stacking interaction with the salicylaldimine plane. As shown in Figure 4 (right), the dihedral angle between the phenyl group and the salicylaldimine plane is 17.4 • , and the distance from the centroid of the phenyl ring to the salicylaldimine plane is 3.40 Å, which are very similar to π-π stacking characteristics in previous reports [49]. Such a weak intramolecular interaction can be further confirmed by RDG analysis.…”

Section: Synthesis and Characterization Of The Titanium Complexessupporting

confidence: 84%

Thermal-Robust Phenoxyimine Titanium Catalysts Bearing Bulky Sidearms for High Temperature Ethylene Homo-/Co- Polymerizations

Wang,

Ma,

Wang

et al. 2024

Polymers

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A family of titanium complexes (Ti1–Ti7) with the general formula LTiCl3, supported by tridentate phenoxyimine [O−NO] ligands (L1–L7) bearing bulky sidearms, were synthesized by treating the corresponding ligands with stoichiometric amount of TiCl4. All the ligands and complexes were well characterized by 1H and 13C NMR spectroscopies, in which ortho- methoxyl groups on N-aryl moieties shifted to downfield, corroborating the successful coordination reaction. Structural optimization by DFT calculations revealed that one of the phenyl groups on dibenzhydryl moiety could form π-π stacking interaction with the salicylaldimine plane, because of which the obtained titanium complexes revealed good thermal stabilities for high-temperature polymerization of ethylene. The thermal robustness of the complexes was closely related to the strength of π-π stacking interactions, which were mainly influenced by the substituents on the dibenzhydryl moieties; Ti1, Ti4 and Ti5 emerged as the three best-performing complexes at 110 °C. With the aid of such π-π stacking interactions, the complexes were also found to be active at >150 °C, although decreased activities were witnessed. Besides homopolymerizations, complexes Ti1–Ti7 were also found to be active for the high-temperature copolymerization of ethylene and 1-octene, but with medium incorporation percentage, demonstrating their medium copolymerization capabilities.

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Section: Synthesis and Characterization Of The Titanium Complexessupporting

confidence: 84%

Thermal-Robust Phenoxyimine Titanium Catalysts Bearing Bulky Sidearms for High Temperature Ethylene Homo-/Co- Polymerizations

Wang,

Ma,

Wang

et al. 2024

Polymers

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“…Aromatic–aromatic interactions − have been invoked as key features of a number of molecular phenomena: protein folding, − crystal engineering, − catalysis, − and drug design. ,− Explanations have suggested that there is something special about these interactions. ,,, However, it has been clearly demonstrated that the aromaticity is not the key as nonaromatic, planar 6π electron systems have stacking energies similar to those of benzene . Here, we will use the term aromatic–aromatic interactions as most observations fall into that category, but our conclusions will apply in other cases.…”

Section: Introductionmentioning

confidence: 99%

What Is Special about Aromatic–Aromatic Interactions? Significant Attraction at Large Horizontal Displacement

et al. 2020

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High-level ab initio calculations show that the most stable stacking for benzene−cyclohexane is 17% stronger than that for benzene− benzene. However, as these systems are displaced horizontally the benzene− benzene attraction retains its strength. At a displacement of 5.0 Å, the benzene−benzene attraction is still ∼70% of its maximum strength, while benzene−cyclohexane attraction has fallen to ∼40% of its maximum strength. Alternatively, the radius of attraction (>2.0 kcal/mol) for benzene−benzene is 250% larger than that for benzene−cyclohexane. Thus, at relatively large distances aromatic rings can recognize each other, a phenomenon that helps explain their importance in protein folding and supramolecular structures.

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“…It is mainly caused by intermolecular overlapping of p orbitals in π-conjugated systems. Based on its stacking patterns, π,π-stacking can be classified into three models: face-to-face (sandwich), edge-to-face (T-shaped), and offset face-to-face (parallel-displaced) [ 3 , 4 ]. Due to its multiplicity and ubiquity, such a non-covalent interaction has been widely explored in many fields of chemistry [ 5 , 6 , 7 , 8 ] and biochemistry [ 9 , 10 , 11 ], and more importantly, it also reveals a decisive role in influencing the course of a reaction [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Half-Titanocene Complexes Containing π,π-Stacked Aryloxide Ligands, and Their Use as Catalysts for Ethylene (Co)polymerizations

Wang

Zhao

et al. 2022

Polymers

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A family of half-titanocene complexes bearing π,π-stacked aryloxide ligands and their catalytic performances towards ethylene homo-/co- polymerizations were disclosed herein. All the complexes were well characterized, and the intermolecular π,π-stacking interactions could be clearly identified from single crystal X-ray analysis, in which a stronger interaction could be reflected for aryloxides bearing bigger π-systems, e.g., pyrenoxide. Due to the formation of such interactions, these complexes were able to highly catalyze the ethylene homopolymerizations and copolymerization with 1-hexene comonomer, even without any additiveson the aryloxide group, which showed striking contrast to other half-titanocene analogues, implying the positive influence of π,π-stacking interaction in enhancing the catalytic performances of the corresponding catalysts. Moreover, it was found that addition of external pyrene molecules was capable of boosting the catalytic efficiency significantly, due to the formation of a stronger π,π-stacking interaction between the complexes and pyrene molecules.

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π–π Interaction Directed Applications of Metal Complexes

Cited by 3 publications

References 72 publications

Thermal-Robust Phenoxyimine Titanium Catalysts Bearing Bulky Sidearms for High Temperature Ethylene Homo-/Co- Polymerizations

Thermal-Robust Phenoxyimine Titanium Catalysts Bearing Bulky Sidearms for High Temperature Ethylene Homo-/Co- Polymerizations

What Is Special about Aromatic–Aromatic Interactions? Significant Attraction at Large Horizontal Displacement

Synthesis of Half-Titanocene Complexes Containing π,π-Stacked Aryloxide Ligands, and Their Use as Catalysts for Ethylene (Co)polymerizations

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