Chemistry of heterocyclic compounds. 81. Palladium(II) complexes of pyridine- and pyrazine-based ligands with trans bis(carbon-metal) bonds. Ligand synthesis, complexation, and crystal structure

Newkome, George R.; Gupta, Vinod K.; Fronczek, Frank R.

doi:10.1021/om00067a004

Cited by 12 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This was expected as supercritical CO2 is a nonpolar system and consequently there is almost no chemical interaction between the metal and CO2. Therefore, it was decided to prepare a CO2-philic polymer bearing several pyridine units, well-known to interact and form complexes with metals like Pd and Pt [34][35][36].…”

Section: Resultsmentioning

confidence: 99%

Promising polymer-assisted extraction of palladium from supported catalysts in supercritical carbon dioxide

Ruiu¹,

Bauer‐Siebenlist²,

Șenilă³

et al. 2020

Journal of CO2 Utilization

View full text Add to dashboard Cite

Precious metals, in particular palladium (Pd), have a wide range of daily applications, from automotive catalysts to fine chemistry production. Nevertheless, these metals are relatively rare and highly expensive, considering their massive industrial utilization. In the last decades, different recycling methods have been explored. Nowadays, the most applied methods, namely pyro-and/or hydrometallurgy, involve energy-intensive processes and/or the generation of large amounts of effluents to be treated. Thus, the development of a more sustainable recycling process of precious metals is highly desirable. In the present work, we introduce a sustainable process based on the use of a green solvent, supercritical CO2, operated under mild conditions (P = 25 MPa and T = 40 °C). The extraction process is possible thanks to the addition of CO2-soluble complexing polymers bearing pyridine units. The proposed method leads to the extraction of more than 70% of Pd from an aluminosilica-supported catalyst.

show abstract

Section: Resultsmentioning

confidence: 99%

Promising polymer-assisted extraction of palladium from supported catalysts in supercritical carbon dioxide

Ruiu¹,

Bauer‐Siebenlist²,

Șenilă³

et al. 2020

Journal of CO2 Utilization

View full text Add to dashboard Cite

show abstract

“…Cyclopalladation reactions involving a C(sp 2 )−H activation are by far the best known, while those involving a C(sp 3 )−H bond are a minority. ,− Those involving a prochiral C(sp 3 )−H bond are very rare. ,, In this paper, we report the synthesis of a family of cyclopalladated complexes with a chiral C(sp 3 ) atom bonded to Pd.…”

Section: Introductionmentioning

confidence: 99%

“…As far as we are aware, the double C-H bond activation reactions leading to 1M2C1L complexes are limited to palladation of a coordinated 2-pyridinesubstituted phosphonium salt 49 and 2,6-pyridine-, 3,3′bipyridine-, and 2-pyrazine-substituted ligands, 42,44,45 while those giving 1M2C2L complexes are known for 2-pyridine-and 2-pyrazine-substituted ligands. [43][44][45] In this paper we report new 1M2C2L complexes.…”

Section: Introductionmentioning

confidence: 99%

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

et al. 1999

View full text Add to dashboard Cite

[PdCl2(NCPh)2] reacts with R−carbonylmethylenethiopyridines [py{SCH2C(O)R}-2] to give, depending on the substituent R and the reaction conditions, or the coordination complexes [Pd{py{SCH2C(O)R}-2}2Cl2] (R = Ph, Me, OMe). The latter can be doubly deprotonated by a base (Na2CO3 or NaH) to give dicyclometalated complexes These transmetalate one ligand to [PdCl2(NCPh)2] to give which in turn reacts with (Me4N)Cl or with monodentate ligands L or with MeCN in the presence of AgClO4 to give anionic neutral [R = Ph, L = PPh3, py{SCH2C(O)Ph}-2, tBuNC, NH2CH(Me)Ph, pyridine (py), tetrahydrothiophene (tht); R = Me, L = PPh3, py, tht], or cationic (R = Ph, Me, OMe) complexes, respectively. The latter react with PPh3 or with bidentate ligands to give complexes or [L = PPh3, L2 = N,N,N‘,N‘-tetramethylethylenediamine (tmeda) or 2,2‘-bipyridine (bipy)]. The crystal structures of and have been determined.

show abstract

“…As an extension of this work, we report herein a complete study on the coordination behavior of ligand 1 – toward a series of d 8 (Pd(II), Rh(I), Ir(I), Au(III)) and d 6 (Ru(II), Mn(I)) transition-metal centers, demonstrating that 1 – is also able to act as a stable, chelating, and LX-type malonate-C(sp 3 )/NHC ligand. Such a malonate-derived σ-alkyl ligand is quite rare in the literature , and, to the best of our knowledge, has been incorporated only twice as a constitutional unit in ancillary ligand …”

Section: Introductionmentioning

confidence: 63%

An Anionic, Chelating C(sp³)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle

et al. 2021

View full text Add to dashboard Cite

The coordination chemistry of the anionic NHC 1 − based on an imidazo[1,5-a]pyridin-3-ylidene (IPy) platform substituted at the C5 position by an anionic barbituric heterocycle was studied with d 6 (Ru(II), Mn(I)) and d 8 (Pd(II), Rh(I), Ir(I), Au(III)) transition-metal centers. While the anionic barbituric heterocycle is planar in the zwitterionic NHC precursor 1•H, NMR spectroscopic analyses supplemented by X-ray diffraction studies evidenced the chelating behavior of ligand 1 − through the carbenic and the malonic carbon atoms in all of the complexes, resulting from a deformation of the lateral barbituric heterocycle. The complexes were obtained by reaction of the free carbene with the appropriate metal precursor, except for the Au(III) complex 10, which was obtained by oxidation of the antecedent gold(I) complex [AuCl(1)] − with PhICl 2 as an external oxidant. During the course of the process, the kinetic gold(I) intermediate 9 resulting from the oxidation of the malonic carbon of the barbituric moiety was isolated upon crystallization from the reaction mixture. The ν CO stretching frequencies recorded for complex [Rh(1)(CO) 2 ] (5) demonstrated the strong donating character of the malonate-C(sp 3 )/NHC ligand 1 − . The ruthenium complex [Ru(1)Cl(p-cymene)] (11) was implemented as a precatalyst in the dehydrogenative synthesis of carboxylic acid derivatives from primary alcohols and exhibited high activities at low catalyst loadings (25−250 ppm) and a large tolerance toward functional groups.

show abstract

Chemistry of heterocyclic compounds. 81. Palladium(II) complexes of pyridine- and pyrazine-based ligands with trans bis(carbon-metal) bonds. Ligand synthesis, complexation, and crystal structure

Cited by 12 publications

References 0 publications

Promising polymer-assisted extraction of palladium from supported catalysts in supercritical carbon dioxide

Promising polymer-assisted extraction of palladium from supported catalysts in supercritical carbon dioxide

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

An Anionic, Chelating C(sp³)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle

Contact Info

Product

Resources

About

Chemistry of heterocyclic compounds. 81. Palladium(II) complexes of pyridine- and pyrazine-based ligands with trans bis(carbon-metal) bonds. Ligand synthesis, complexation, and crystal structure

Cited by 12 publications

References 0 publications

Promising polymer-assisted extraction of palladium from supported catalysts in supercritical carbon dioxide

Promising polymer-assisted extraction of palladium from supported catalysts in supercritical carbon dioxide

Multidonor Ligands. 3. Cyclopalladation of py{SCH2C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp3)−H Bond Activation

An Anionic, Chelating C(sp3)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle

Contact Info

Product

Resources

About

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

An Anionic, Chelating C(sp³)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle