Synthesis of Novel Palladium Complexes Containing β‐Diketonate and NHC Ligands and their Catalytic Ability for Addition Polymerizations of the Functional Norbornenes

Lee, Dong Jin; Kim, Myungwoong; Kim, Chan Kyung; Lee, Ik Mo

doi:10.1002/bkcs.11761

Cited by 10 publications

(14 citation statements)

References 23 publications

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“…9 More specifically, the fluorinated β-diketone 1,1,1,5,5,5-hexafluoroacetylacetone (Hhfac) ligand imparts volatility. 10−12 Although complexes of the type Ln(hfac) 3 (H 2 O) x have been known for over 50 years, 13 only the single-crystal structures of the later lanthanides Tb, 14 Ho, 15 Er, 16 and Dy 17 are currently known. The early lanthanides (La-Nd) have differing hydration numbers and are structurally different based on powder X-ray diffraction (PXRD) patterns compared to later lanthanides.…”

Section: ■ Introductionmentioning

confidence: 99%

Mechanochemical Syntheses of Ln(hfac)₃(H₂O)_x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)_n Complexes

et al. 2022

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Volatile lanthanide coordination complexes are critical to the generation of new optical and magnetic materials. One of the most common precursors for preparing volatile lanthanide complexes is the hydrate with the general formula Ln(hfac) 3 (H 2 O) x (x = 3 for La-Nd, x = 2 for Sm) (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato). We have investigated the synthesis of Ln(hfac) 3 (H 2 O) x using more environmentally sustainable mechanochemical approaches. Characterization of the products using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis, and powder X-ray diffraction shows substantial differences in product distribution between methods. The mechanochemical synthesis of the hydrate complexes leads to a variety of coordination compounds including the expected hydrate product, the known retro-Claisen impurity, and hydrated protonated Hhfac ligand depending on the technique employed. Surprisingly, 10-coordinate complexes of the form Na 2 Ln(hfac) 5 •3H 2 O for Ln = La-Nd were also isolated from reactions using a mortar and pestle. The electrostatic bonding of lanthanide coordination complexes is a challenge for obtaining reproducible reactions and clean products. The reproducibility issues are most acute for the large, early lanthanides whereas for the mid to late lanthanides, reproducibility in terms of product distribution and yield is less of an issue because of their smaller size and greater charge to radius ratio. Ball milling increases reproducibility in terms of generating the desired Ln(hfac) 3 (H 2 O) x along with hydrated Hhfac (tetraol) and free Hhfac products. The results illustrate the dynamic behavior of lanthanide complexes in solution and the solid state as well as the structural diversity available to the early lanthanides.

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Section: ■ Introductionmentioning

confidence: 99%

Mechanochemical Syntheses of Ln(hfac)₃(H₂O)_x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)_n Complexes

et al. 2022

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“…0.3 mg/mL calculated with respect to biphenyl used as the internal standard). The Pd complexes used in this work were prepared starting from commercially available PdCl 2 following procedures reported in the literature . Compounds 1a – m , 1o – p , 1y-aa , and 1ac were prepared according to previously reported procedures.…”

Section: Methodsmentioning

confidence: 99%

“…The Pd complexes used in this work were prepared starting from commercially available PdCl 2 following procedures reported in the literature. 31 Compounds 1a – m , 1o – p , 1y-aa , 19c and 1ac ( 32 ) were prepared according to previously reported procedures. Procedures for the preparation of compounds 1n and 1q – x are reported in the Supporting Information .…”

Section: Methodsmentioning

confidence: 99%

Formic Acid as Carbon Monoxide Source in the Palladium-Catalyzed N-Heterocyclization of o-Nitrostyrenes to Indoles

2023

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The reductive cyclization reaction of o-nitrostyrenes to generate indoles has been investigated for three decades using CO as a cheap reducing agent, but it remains an interesting area of research and improvements. However, using toxic CO gas has several drawbacks. As a result, it is highly preferable to use safe and efficient surrogates for in situ generation of CO from nontoxic and affordable sources. Among several CO sources that have been previously explored for the generation of gaseous CO, here we report the use of cheap and readily available formic acid as an effective reductant for the reductive cyclization of o-nitrostyrenes. The reaction is air and water tolerant and provides the desired indoles in yields up to 99%, at a low catalyst loading (0.5 mol %) and without generating toxic or difficult to separate byproducts. A cheap glass thick-walled "pressure tube" can be used instead of less available autoclaves, even on a 2 g scale, thus widening the applicability of our protocol.

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“…Considering different cycloolefins, norbornenes attract the attention of researchers as model monomers for catalytic activity tests and as building blocks for new polymeric materials owing to the diversity of norbornene chemistry, their availability, and the high reactivity of norbornene double bonds. A huge number of two- and three-component systems based on transition metal salts which are the most widely used catalysts for VAP of norbornenes ,,,,− have been developed. However, these systems have a number of known disadvantages when compared to single-component catalysts. ,, At the same time, single-component catalysts for VAP of norbornenes are rare, and single-component catalysts capable of catalyzing living VAP of norbornenes are scarce.…”

Section: Introductionmentioning

confidence: 99%

Air-Stable Single-Component Pd-Catalysts for Vinyl-Addition Polymerization of Functionalized Norbornenes

et al. 2022

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Well-defined single-component and tolerant Ru-, Mo-, and W-catalysts have been earlier developed for ring-opening metathesis polymerization of norbornene and its derivatives. Another way of norbornene polymerization�vinyl-addition polymerization (VAP)�is a more thermodynamically favorable process and gives polymers with saturated and rigid main chains. Single-component catalysts for VAP are required, which combine good activity, tolerance to functional groups, resistance to oxygen, and air moisture and are capable of catalyzing living VAP of norbornenes. Herein, we have shown that cationic Pd-complexes with N-heterocyclic carbene ligands (NHC ligands) and weak coordinating anion ligands ([(NHC)Pd(allyl)L] + A − , where allyl is an allyl group, L = CO, CH 3 CN, CH 2 Cl 2 , and A − = SbF 6 − or BARF − ) are highly efficient single-component catalysts for VAP of both norbornene and various substituted norbornenes. These complexes, being stable in the solid state and in solutions, have exhibited several important features as VAP catalysts. They are capable of catalyzing VAP of norbornenes in air and are tolerant to functional groups. The complexes have shown high catalytic activity and have allowed polymerizing monomers at very low catalyst loadings, as low as 2 ppm. The versatility of [(NHC)Pd(allyl)L] + A − complexes as catalysts of VAP has been demonstrated by successful polymerization of monomers with polar and bulky groups, containing alkyl, vinyl, alkylidene, ether, ester, imide, or organosilicon motifs, affording high-molecular-weight products in good and high yields. Tuning the nature of NHC and allyl ligands in [(NHC)Pd(allyl)L] + A − complexes let perform living VAP, yielding block copolymers.

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Synthesis of Novel Palladium Complexes Containing β‐Diketonate and NHC Ligands and their Catalytic Ability for Addition Polymerizations of the Functional Norbornenes

Cited by 10 publications

References 23 publications

Mechanochemical Syntheses of Ln(hfac)₃(H₂O)_x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)_n Complexes

Mechanochemical Syntheses of Ln(hfac)₃(H₂O)_x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)_n Complexes

Formic Acid as Carbon Monoxide Source in the Palladium-Catalyzed N-Heterocyclization of o-Nitrostyrenes to Indoles

Air-Stable Single-Component Pd-Catalysts for Vinyl-Addition Polymerization of Functionalized Norbornenes

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Synthesis of Novel Palladium Complexes Containing β‐Diketonate and NHC Ligands and their Catalytic Ability for Addition Polymerizations of the Functional Norbornenes

Cited by 10 publications

References 23 publications

Mechanochemical Syntheses of Ln(hfac)3(H2O)x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)n Complexes

Mechanochemical Syntheses of Ln(hfac)3(H2O)x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)n Complexes

Formic Acid as Carbon Monoxide Source in the Palladium-Catalyzed N-Heterocyclization of o-Nitrostyrenes to Indoles

Air-Stable Single-Component Pd-Catalysts for Vinyl-Addition Polymerization of Functionalized Norbornenes

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Mechanochemical Syntheses of Ln(hfac)₃(H₂O)_x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)_n Complexes

Mechanochemical Syntheses of Ln(hfac)₃(H₂O)_x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)_n Complexes