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

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...

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Published in:Applied organometallic chemistry 2022-02, Vol.36 (2), p.n/a
Main Authors: 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
Format: Article
Language:English
Subjects:
bifunctional catalyst
Catalysts
Catalytic activity
Chemical analysis
Chemistry
Ethylene
Fourier transforms
Hydrazones
Infrared spectroscopy
Ions
Mass spectrometry
Metathesis
NMR
norbornene
Nuclear magnetic resonance
Palladium
polyethylene
Polymerization
polyNBE
Reaction time
Ring opening
Ruthenium
Toluene
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Summary: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. New heterobimetallic complex containing Ru(II) and Pd(II) linked by an pyridine‐hydrazone ligand was synthesized and fully characterized. The Ru‐Pd and mono‐Ru complexes were applied in ring‐opening metathesis polymerization (ROMP) of norbornene. The Ru‐Pd and mono‐Pd complexes were applied in ethylene polymerization. The optimum conditions of reaction on ROMP and ethylene polymerization were evaluated, rea
ISSN:0268-2605
1099-0739
DOI:10.1002/aoc.6491