3145-77-5Relevant academic research and scientific papers
Thermodynamic and kinetic behaviour of [Pt(2-methylthiomethylpyridine) (OH2)2]2+
Hochreuther, Stephanie,Nandibewoor, Sharanappa T.,Puchta, Ralph,Van Eldik, Rudi
, p. 512 - 522 (2012)
The diaqua complex [Pt(2-methylthiomethylpyridine)(OH2) 2]2+, Pt(mtp), was synthesized and investigated thermodynamically as well as kinetically. Spectrophotometric acid-base titrations were performed to determine the pKa values of the two coordinated water ligands. A low pKa1 value of 3.15 was observed for the water molecule trans to the pyridine donor, whereas a pKa2 value of 6.84 was found for the water molecule trans to the labilising sulphur donor. The substitution of coordinated water by a series of sterically hindered S-containing nucleophiles, viz. thiourea (tu), N,N′-dimethylthiourea (dmtu) and N,N,N′,N′-tetramethylthiourea (tmtu), was studied under pseudo first-order conditions as a function of nucleophile concentration, pH (2, 4.75, 7.4), temperature and pressure, using stopped-flow techniques and UV-vis spectroscopy. In general the first substitution reaction takes place trans to the sulphur donor. At pH 2 the nucleophiles react in the order tu (634 ± 10) > dmtu (507 ± 5) ? tmtu (165 ± 3 M-1 s -1 at 25 °C), which is caused by steric hindrance. The second observed reaction involves two steps, viz. the displacement of the second water ligand and dechelation of the pyridine ring with the third-order rate constants 73.3 ± 0.8 (tu), 22.1 ± 0.1 (dmtu) and 6.8 ± 0.2 M -2 s-1 (tmtu) at 25 °C. At pH 4.75 the reactions are in general slower due to the presence of aqua-hydroxo species. The same order in reactivity was found, viz. tu (106 ± 1) > dmtu (72 ± 1) ? tmtu (14.1 ± 0.5 M-1 s-1 at 25 °C). No evidence for ring-dechelation could be observed under these conditions. At pH 7.4 the inert dihydroxo species is predominantly present in solution and consequently no substitution reaction was observed. Quantum chemical calculations were performed to support the interpretation and discussion of the experimental results.
Emissive Ruthenium-Bisdiimine Complexes with Chelated Thioether Donors
Wallenstein, Joachim Hedberg,Sundberg, Jonas,McKenzie, Christine J.,Abrahamsson, Maria
, p. 897 - 906 (2016)
The photophysical properties of ruthenium(II) complexes of bidentate 2-[(alkylthio)methyl]pyridine (N,S) ligands have been systematically investigated. The co-ligands in the heteroleptic complexes were diimines (N,N ligands, e.g., bpy, phen) or tripodal tetradentate tris(2-pyridylmethyl)amine (tpa). Their X-ray structures revealed little variation in the Ru-S (2.31-2.33 ?) and Ru-N (2.06-2.11 ?) bond lengths. Despite this, considerable variation can be observed in the electrochemistry and spectroscopy measurements. The presence of the thioether sulfur donor results in a shift to a more positive potential of the Ru2+/Ru3+ process, and the absorption maxima are consequently blueshifted in [Ru(N,N)2(N,S)]2+ complexes compared with the [Ru(N,N)3]2+ analogues. The [Ru(N,N)2(N,S)]2+ complexes display strong room-temperature emission from 3MLCT states, governed by the N,N donors. This is corroborated by low-temperature steady-state emission studies, which revealed typical 3MLCT emission profiles and excited-state lifetimes of around 5-10 μs.
A study on the BF3-directed lithiation of 2-picoline and 2,3-lutidine
Dhau, Jaspreet S.,Singh, Amritpal
, p. 109 - 114 (2013/11/06)
The lithiation of 2-picoline (1a) and 2,3-lutidine (1b) in diethyl ether has been investigated with and without prior complexation with BF3. The reactions of the BF3 adduct of these moieties (2a and 2b) with lithium diisopropylamide (LDA) and subsequent trapping with benzaldehyde or dimethyl disulfide gave products corresponding to exclusive lithiation at the α-methyl carbon. The yields obtained with these reactions were far superior to that obtained with the lithiation of uncomplexed 1a and 1b. The dilithiation of 2a and 2b has also been investigated and a convenient and efficient synthesis of the diiodo derivatives of 1,2-bis(pyridin-2-yl)ethane has been provided.
Synthesis and structure of dichloropalladium(II) complexes of heteroleptic N,S- and N,Se-donor ligands based on the 2-organochalcogenomethylpyridine motif, and Mizoroki-Heck catalysis mediated by complexes of N,S-donor ligands
Jones, Roderick C.,Canty, Allan J.,Gardiner, Michael G.,Skelton, Brian W.,Tolhurst, Vicki-Anne,White, Allan H.
scheme or table, p. 77 - 87 (2010/04/01)
Ligands containing the 2-organochalcogenomethylpyridine motif with substituents in the 4- or 6-position of the pyridyl ring, R4,R6-pyCH2ER1 [R4 = R6 = H, ER1 = SMe (1), SeMe (2), SPh (6), SePh (7); R4 = Me, R6 = H, ER1 = SMe (3), SPh (8), SePh (9); R4 = H, R6 = Me, ER1 = SMe (4), SPh (10), SePh (11); R4 = H, R6 = Ph, ER1 = SMe (5), SPh (12), SePh (13)] are obtained on the reaction of R4,R6-pyMe with LiBun followed by R1EER1. On reaction with PdCl2(NCMe)2, the ligands with a 6-phenyl substituent form cyclopalladated species PdCl{6-(o-C6H4)pyCH2ER1-C,N,E} (5a, 12a, 13a) with the structure of 13a (ER1 = SePh) confirmed by X-ray crystallography; other ligands form complexes of stoichiometry PdCl2(R4,R6-pyCH2ER1). Complexes with R6 = H are monomeric with N,E-bidentate configurations, confirmed by structural analysis for 3a (R4 = Me, ER1 = SMe), 7a (R4 = H, ER1 = SePh) and 9a (R4 = Me, ER1 = SePh). Two of the 6-methyl substituted complexes examined by X-ray crystallography are oligomeric with trans-PdCl2(N,E) motifs and bridging ligands, trimeric [PdCl2(μ-6-MepyCH2SPh-N,S)]3 (10a) and dimeric [PdCl2(μ-6-MepyCH2SePh-N,Se)]2 (11a). This behaviour is attributed to avoidance of the Me···Cl interaction that would occur in the cis-bidentate configuration if the pyridyl plane had the same orientation with respect to the coordination plane as observed for 3a, 7a and 9a [dihedral angles 8.0(2)-16.8(2)°]. When examined as precatalysts for the Mizoroki-Heck reaction of n-butyl acrylate with aryl halides in N,N-dimethylacetamide at 120 °C, the complexes exhibit the anticipated trends in yield (ArI > ArBr > ArCl, higher yield for electron withdrawing substituents in 4-RC6H4Br and 4-RC6H4Cl). The most active precatalysts are PdCl2(R4-pyCH2SMe-N,S) (R = H (1a), Me (3a)); complexes of the selenium containing ligands exhibit very low activity. For closely related ligands, the changes SMe to SPh, 6-H to 6-Me, and 6-H to 6-Ph lead to lower activity, consistent with involvement of both the pyridyl and chalcogen donors in reactions involving aryl bromides. The precatalyst PdCl2(pyCH2SMe-N,S) (1a) exhibits higher activity for the reaction of aryl chlorides in Bun4NCl at 120 °C as a solvent under non-aqueous ionic liquid (NAIL) conditions. Crown Copyright
The methyl group as a source of structural diversity in heterocyclic chemistry: Side chain functionalization of picolines and related heterocycles
Mamane, Victor,Aubert, Emmanuel,Fort, Yves
, p. 7294 - 7300 (2008/02/11)
(Chemical Equation Presented) The reaction of 2-picoline at the methyl group with NDA and KDA followed by dimethyldisulfide trapping furnished, respectively, dithioacetals and trithioortho esters with high selectivity. The method was successfully applied to other methyl-substituted pyridines, quinolines, and pyrazines. Dithioketals were prepared by a one-pot procedure involving the reaction of metalated 2-picoline with 2 equiv of dimethyldisulfide followed by in situ trapping with a second electrophile. All of the generated thio-substituted compounds were efficiently transformed in presence of mercury salts or under oxidizing conditions to other functional groups comprising aldehydes, ketones, ketals, thiol esters, orthoesters, and esters.
Biotransformation of organic sulfides. Part 12. Conversion of heterocyclic sulfides to chiral sulfoxides by Helminthosporium sp. NRRL 4671 and Mortierella isabellina ATCC 42613
Holland, Herbert L.,Turner, Carl D.,Andreana, Peter R.,Nguyen, Doan
, p. 463 - 471 (2007/10/03)
The enantioselective oxidation of a series of heterocyclic prochiral sulfides to chiral sulfoxides has been examined using the fungal biocatalysts Helminthosporium species NRRL 4671 and Mortierella isabellina ATCC 42613. Methylthiofuranyl and -thiophenyl
Facile Synthesis of 2-pyridines and Phenyl-Substituted Derivatives
Kiselyov, Alexander S.,Strekowski, Lucjan
, p. 329 - 332 (2007/10/02)
The title compounds 5 are produced in the reaction of N-fluoropyridinium tetrafluoroborate (1) with sulfides 2.The proposed mechanism involves single-electron transfer from 2 to 1 followed by transformations of the resultant radical intermediates.
Synthesis of new optically active sulfoxides with chelating properties
Baldenius, Kai-U.,Kagan, Henri B.
, p. 597 - 610 (2007/10/02)
Access to enantiomerically pure 2-pyridinylmethyl sulfoxides and β-imino sulfoxides was sought.The latter were obtained in tautomeric mixtures with their enamines by condensation of optically active β-keto sulfoxides with primary amines. 2-Pyridinylmethyl
