Monometallic and heterobimetallic ruthenium (II) and palladium (II) complexes based on a pyridine‐hydrazone ligand as bifunctional catalysts for ROMP of norbornene and ethylene polymerization.

Autor: Gois, Patrik Dione de Santana, Maia, Juliana Iris Pereira, Masson, Gustavo Henrique Cicero, Martins, Daniele Maria, Machado, Antonio Eduardo da Hora, Goi, Beatriz Eleutério, Maia, Pedro Ivo da Silva, Carvalho‐Jr, Valdemiro Pereira de
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Zdroj: Applied Organometallic Chemistry; Feb2022, Vol. 36 Issue 2, p1-14, 14p
Abstrakt: The monometallic complex [Pd(L)(PPh3)] (mono‐Pd) was synthesized using a potentially tridentate hydrazone (H2L) and used as precursor to prepare a heterobimetallic ruthenium (II)‐palladium (II) complex [Cl2(p‐cymene)Ru(μ‐L)Pd (PPh3)] (Ru‐Pd). Mono‐Pd and Ru‐Pd were characterized by fourier transform infrared spectroscopy (FTIR), ultraviolet‐visible spectroscopy (UV–Vis), 1H, 13C{1H} and 31P{1H} nuclear magnetic ressonance(NMR) spectroscopy, elemental analysis, cyclic voltammetry, matrix‐assisted laser desorption/ionization ‐ time of flight (MALDI‐TOF) mass spectrometry, and computational methods. The mono‐Pd was additionally studied by single‐crystal X‐ray diffraction. The complex [RuCl2(p‐cymene)(Isoniazid)] (mono‐Ru) was also obtained following literature methods aiming a comparison in the catalytic activity. The ring opening metathesis polymerization (ROMP) of norbornene (NBE) using mono‐Ru or Ru‐Pd as precatalysts in the presence of ethyl diazoacetate (EDA) was evaluated as a function of time (10–60 min) using [NBE]/[EDA]/[Ru] = 5000/28/1 at 50°C. The time increases produced good yields of polyNBE, reaching 38% and 46% for mono‐Ru and Ru‐Pd, respectively. The polyNBE produced was measured by size‐exclusion chromatography (SEC) and reached an order of magnitude of 105 g·mol−1 of Mn, with Ð values ranging from 2.51 to 1.86 for mono‐Ru and from 3.50 to 1.66 for Ru‐Pd. The catalytic activity of mono‐Pd and Ru‐Pd on ethylene polymerization was assessed with a range of [Al]/[Pd] molar ratio between 350 and 1750, 30–70°C temperature, 2 to 4 h reaction time, and total reaction volume of 25 and 50 ml. Mono‐Pd achieved an activity of 22.80 kg PE (mol Pd)−1 h−1 at 60°C after 4 h using [Al]/[Pd] = 1050, 7 μmol of catalyst in 25 ml of toluene, and 116 psi ethylene. For Ru‐Pd, an activity of 20.35 kg PE (mol Pd)−1 h−1 at 60°C after 4 h was obtained using [Al]/[Pd] = 1750, 7 μmol of catalyst in 25 ml of toluene, and 116 psi ethylene. Overall, Ru‐Pd showed to be active in both ROMP and ethylene polymerization reactions, being categorized as a bifunctional catalyst. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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