14267-08-4Relevant academic research and scientific papers
Kinetic selection of Pd4L2metallocyclic and Pd6L3trigonal prismatic assemblies
O’Connor, Helen M.,Coletta, Marco,Etcheverry-Berríos, Alvaro,Nichol, Gary S.,Brechin, Euan K.,Lusby, Paul J.
, p. 11799 - 11802 (2020)
The self-assembly of Pd4L2metallocylcic and Pd6L3trigonal prismatic assemblies are described. The selection of one species over the other has been achieved by careful choice of ancilliary ligands, which switch the dynamics of the Pd-pyridine bonds such that a highly unusual and distorted smaller assembly can be kinetically trappeden routeto the more energetically favourable larger species. Both assemblies provide promise as easy to access multicavity reaction vessels.
Combining the reactivity properties of pcy3 and P t Bu3 into a single ligand, P(i Pr)(t Bu)2. reaction via mono- or bisphosphine palladium(0) centers and palladium(i) dimer formation
Proutiere, Fabien,Lyngvi, Eirik,Aufiero, Marialuisa,Sanhueza, Italo A.,Schoenebeck, Franziska
, p. 6879 - 6884 (2014)
Trialkylphosphine ligands are ubiquitous in catalysis. Via modulation of the steric bulk of these ligands, two central aspects that dictate reactivity and selectivity in catalysis can be controlled: i.e., the coordination sphere and favored oxidation stat
Preparation of (Chloromethyl)palladium(II) Derivatives from Complexes of Palladium Dichloride by Reaction with Diazomethane or Bis(chloromethyl)-mercury
McCrindle, Robert,Arsenault, Gilles J.,Farwaha, Rajeev,McAlees, Alan J.,Sneddon, David W.
, p. 761 - 766 (1989)
Treatment, with diazomethane, of a range of palladium dichloride and dibromide complexes containing chelaing ligands has been examined.With all but one, the formation of a mono(halogenomethyl) product was observed.The methylene insertion products from complexes of palladium dichloride are relatively stable if at least one olefin or phosphine ligand is present, but with bis-amine or -sulphide ligands the insertion products could not be isolated.However, all of the insertion products showed at least some tendency to revert to the starting dichloro complexes by loss of the methylene moiety.Products of insertion into a Pd-Br bond are less readily formed than those of the corresponding chloride and the resulting bromomethyl derivatives are less stable than their chloromethyl analogues.Chloromethyl derivatives were also prepared from the dichloride by treatment with bis(chloromethyl)mercury (only one of the two chloromethyl groups is transfered) or from a performed chloromethyl complex by ligand exchange.
Synthesis of (MeCN)2Pd(CF3)OTs, a general precursor to palladium(II) trifluoromethyl complexes LPd(CF3)X
King, Ryan P.,Buchwald, Stephen L.
, p. 3490 - 3493 (2019)
In palladium-catalyzed aryl-trifluoromethyl cross-coupling reactions, reductive elimination is often the rate-limiting step. Stoichiometric studies of reductive elimination have proved effective in evaluating the ability of various ligands to facilitate t
Double-Decker Coordination Cages
Bandi, Sreenivasulu,Samantray, Sagarika,Chakravarthy, Rajan Deepan,Pal, Amlan K.,Hanan, Garry S.,Chand, Dillip Kumar
, p. 2816 - 2827 (2016)
Bis(pyridin-3-ylmethyl) pyridine-3,5-dicarboxylate (L) possessing one internal and two terminal pyridine moieties displayed differential coordination ability when combined with suitable PdIIcomponents. The compound L acted as a bidentate chelating ligand to form mononuclear complexes when combined with cis-[Pd(tmeda)(NO3)2] or Pd(NO3)2in calculated ratios. The combination of Pd(NO3)2with L in a ratio of 3:4, however, afforded the trinuclear “double-decker” cage [(NO3)2?Pd3(L)4](NO3)4, in which L acts as a nonchelating tridentate ligand and the counter anion (i.e., NO3–) acts as template. The encapsulated NO3–can be replaced by F–, Cl–, or Br–but not by I–. The F–-encapsulated cage could not be isolated due to its reactivity, whereas the Cl–or Br–encapsulated cages could be isolated. Although anionic guests such as NO3–, Cl–, or Br–stabilized the cages, the presence of excess Cl–or Br–(not NO3–) facilitated decomplexation reactions releasing the ligand. The complexation of Pd(Y)2(Y = BF4–, PF6–, CF3SO3–, or ClO4–) with L afforded the corresponding mononuclear complexes under appropriate conditions. However, these counter anions could not act as templates for the construction of double-decker cages.
Selective hydrolysis of the unactivated peptide bond in N-acetylated L-histidylglycine catalyzed by various palladium(II) complexes: Dependence of the hydrolysis rate on the steric bulk of the catalyst
Djuran, Milo? I,Milinkovi?, Sne?ana U
, p. 959 - 963 (2000)
Hydrolytic reactions between various palladium(II) complexes of the type cis-[Pd(L)(H2O)2]2+ in which L is a chelating diamine (ethylenediamine, en; 1,2-propylenediamine, 1,2-pn; N-methylethylenediamine, Meen; isobutylenediamine, ibn and N,N,N',N'-tetramethylethylenediamine, Me4en) or S,N-coordinated amino acid (S-methyl L-cysteine, MeS-L-HCys and L-methionine, L-HMet) and N-acetylated L-histidylglycine (MeCO-His-Gly), were studied by 1H NMR spectroscopy. The reactions were carried out in the pH range 2.0-2.5 and at 60°C. In all these reactions, a palladium(II) complex bound to a histidine residue effects the regioselective cleavage of the amide bond involving the carboxylic group of histidine. We found that the rate of hydrolysis decreases as the steric bulk of the palladium(II) complex increases (en > 1,2-pn > Meen > MeS-L-HCys > ibn > L-HMet > Me4en). The observed rates of hydrolytic reaction are discussed in terms of steric hindrance of the chelating diamine or sulfur-containing amino acid on the palladium(II) complexes. This study is an important step in the development of new palladium(II) complexes as artificial metallopeptidases. (C) 2000 Elsevier Science Ltd.
Metal-binding sites of N-acetylneuraminic acid
Illi, Sarah,Schulten, Johanna,Kluefers, Peter
, p. 77 - 83 (2013)
Sialic acid represents a group of thirty derivates of neuraminic acid with various substituents at the amino residue and the alcoholic hydroxy groups. We analysed the behaviour of the tetracoordinated metal ions palladium(II) and silicon(IV) against the most important derivative N-acetylneuraminic acid (NANA). The molecular structures were assigned by a combined 1H, 13C and 29Si NMR-spectroscopic approach. Despite the presence of many different functional groups, the coordination chemistry of NANA with PdII follows established rules. Coordination via the N-acetyl-group - sterically impossible with PdII - was realised with SiIV. Copyright
Selective Co-Encapsulation Inside an M6L4Cage
Leenders, Stefan H. A. M.,Becker, René,Kumpulainen, Tatu,de Bruin, Bas,Sawada, Tomohisa,Kato, Taito,Fujita, Makoto,Reek, Joost N. H.
supporting information, p. 15468 - 15474 (2016/10/13)
There is broad interest in molecular encapsulation as such systems can be utilized to stabilize guests, facilitate reactions inside a cavity, or give rise to energy-transfer processes in a confined space. Detailed understanding of encapsulation events is required to facilitate functional molecular encapsulation. In this contribution, it is demonstrated that Ir and Rh-Cp-type metal complexes can be encapsulated inside a self-assembled M6L4metallocage only in the presence of an aromatic compound as a second guest. The individual guests are not encapsulated, suggesting that only the pair of guests can fill the void of the cage. Hence, selective co-encapsulation is observed. This principle is demonstrated by co-encapsulation of a variety of combinations of metal complexes and aromatic guests, leading to several ternary complexes. These experiments demonstrate that the efficiency of formation of the ternary complexes depends on the individual components. Moreover, selective exchange of the components is possible, leading to formation of the most favorable complex. Besides the obvious size effect, a charge-transfer interaction may also contribute to this effect. Charge-transfer bands are clearly observed by UV/Vis spectrophotometry. A change in the oxidation potential of the encapsulated electron donor also leads to a shift in the charge-transfer energy bands. As expected, metal complexes with a higher oxidation potential give rise to a higher charge-transfer energy and a larger hypsochromic shift in the UV/Vis spectrum. These subtle energy differences may potentially be used to control the binding and reactivity of the complexes bound in a confined space.
An efficient method for sterically demanding Suzuki-Miyaura coupling reactions
Zhao, Qing,Li, Chengxi,Senanayake, Chris H.,Tang, Wenjun
supporting information, p. 2261 - 2265 (2013/03/28)
An efficient method for sterically demanding Suzuki-Miyaura coupling reactions has been developed with two catalysts, Pd/BI-DIME (see scheme) and Pd/phenanthrene-based ligand. The Pd/BI-DIME catalyst facilitates the syntheses of extremely hindered biaryls
Pd complexes with trans-chelating ligands composed of two pyridyl groups and rigid π-conjugated backbone
Jung, Miso,Suzaki, Yuji,Saito, Takashi,Shimada, Kyoichi,Osakada, Kohtaro
, p. 168 - 174 (2012/08/28)
1,2-Bis(2-pyridylethynyl)benzene derivatives, having two pyridyl groups and π-conjugated backbone, were prepared from the 1:2 Sonogashira reaction of 1,2-diiodobenzene with 2-alkynyl pyridines. The obtained ligands react with the palladium(II) complexes such as [PdCl2(cod)] and [PdCl 2(MeCN)2] to form the complexes with the ligands coordinated in a trans-chelating bidentate mode. The ligand obtained from 1,3-diiodobenzene and 2-alkynyl pyridine bridges two Pd(II) centers, yielding a dipalladium complex. A dichloropalladium complex with the trans-chelating ligand, containing two methoxy groups in the central arylene group, promotes coupling of phenyl lithium and of phenyl acetylene to yield the respective homo-coupling products. The ligand displacement reactions of {bis(2-pyridylethynyl)benzene}palladium(II) complex with phosphine and dinitrogen ligands, such as PPh3, dppe, dppb, en, tmeda, bpy and phen, takes place smoothly to release the trans-chelating ligand.
