366-18-7Relevant articles and documents
INVESTIGATION OF THE INTERACTION OF PYRIDINE WITH THE SURFACE OF LAMINAR SILICATES BY THE METHOD OF OPTICAL ELECTRONIC SPECTROSCOPY.
Sivalov,Tarasevich
, p. 214 - 218 (1981)
A study of the nature of the active sites on the surface of laminar silicates and an attempt to identify those that are responsible for the observed conversion of sorbed pyridine on the surface of laminar silicate to more complex formations characterized by a rather developed system of conjugated pi -bonds are discussed.
Cartwright et al.
, p. 211,212, 218, 219 (1979)
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Dearmond et al.
, p. 3388,3391 (1979)
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Cation-Assisted Ligand Photosubstitution in Transition-Metal Complexes. Photoreactions of Ru(bpy)32+ with Ag+ in Acetonitrile
Foreman, T. K.,Bonilha, J. B. S.,Whitten, D. G.
, p. 3436 - 3439 (1982)
Irradiation of Ru(bpy)32+ in the presence of Ag+ in acetonitrile leads to the photosubstitution product Ru(bpy)2(CH3CN)22+.The reaction does not occur in the absence of Ag+ or acetonitrile; although Ag+ quenches the luminescent MLCT state of Ru(bpy)32+, a kinetic analysis indicates the photosubstitution does not originate from this excited state.The most reasonable mechanism for the process involves decay of the MLCT state via a d-d excited state to a ligand-labilized intermediate which is interpreted by Ag+ in a process which assists the substitution by removal of a bpy ligand.This mechanism is thus parallel to anion-induced substitution reactions which evidently proceed via competitive anion-ligand capture of the same or similar intermediates.
Acid directed in situ oxidation and decarboxylation of 4,4′,6, 6′-tetra-methyl-2,2′-bipyridine: Synthesis and structural characterisation of 4,4′,6-tri-carboxy-2,2′-bipyridine and its copper(II) coordination polymer
Kelly, Niamh R.,Goetz, Sandrine,Hawes, Chris S.,Kruger, Paul E.
, p. 102 - 109 (2013)
The reaction of either 4,4′,6,6′-tetramethyl-2,2′- bipyridine, L, or 4,4′,6,6′-tetracarboxy-2,2′-bipyridine, H4L, with Cu(OAc)2·H2O under acidic hydrothermal conditions (50:1 H2O/HNO3; 160 °C) led to the formation of crystalline {[Cu(HL′)(H2O)]·H 2O}, 1, which was structurally characterised to identify H 3L′ as 4,4′,6-tricarboxy-2,2′-bipyridine. Clearly, in situ mono-decarboxylation of a tetracarboxylic acid ligand gave the tricarboxy-analogue, H3L′. The structure of 1 consists of a 1D coordination polymer that cross-links through hydrogen-bonding between adjacent carboxylic acid and carboxylate groups, as well as through an aqua ligand and lattice water molecule, to form a densely interconnected 3D network. Regioselective mono-decarboxylation of L or H4L at the 6′-carboxylic acid position may also be affected by heating L or H 4L in acidic solution under hydrothermal conditions (2:1 H 2O/HNO3; 160°C) to yield crystalline 4,4′,6-tricarboxy-2,2′-bipyridinium nitrate hydrate {[H 4L′][NO3]·H2O}, 2, which was also structural characterised. The structure of 2 features an array of hydrogen-bonding interactions that generate a 3D network. More forceful heating of the acidic solution at 180°C led to double decarboxylation and the formation of 4,4′-dicarboxy-2,2′-bipyridine, whereas heating at 200°C led to total decarboxylation and the formation of 2,2′- bipyridine. Details of the structures of 1 and 2 along with their synthesis are discussed.
DIMER FORMATION IN THE REACTION OF ARYL HALIDES CATALYZED BY NICKEL COMPLEXES
Budnikova, Yu. G.,Kargin, Yu. M.,Yanilkin, V. V.
, p. 1299 - 1300 (1992)
The synthesis of diaryls catalyzed by electrochemically generated zero-valent nickel with 2,2'-dipyridyl as the ligand was carried out from aryl halides in high yield.Feasibility was demonstrated for synthesizing the catalyst itself by the anodic dissolution of nickel in the presence of 2-bromopyridine in a diaphragmless cell.Keywords: synthesis, diaryls, aryl halides.
Phototoxicity of strained Ru(II) complexes: Is it the metal complex or the dissociating ligand?
Azar, Daniel F.,Audi, Hassib,Farhat, Stephanie,El-Sibai, Mirvat,Abi-Habib, Ralph J.,Khnayzer, Rony S.
, p. 11529 - 11532 (2017)
A photochemically dissociating ligand in Ru(bpy)2(dmphen)Cl2 [bpy = 2,2′-bipyridine; dmphen = 2,9-dimethyl-1,10-phenanthroline] was found to be more cytotoxic on the ML-2 Acute Myeloid Leukemia cell line than Ru(bpy)2(H2O)22+ and prototypical cisplatin. Our findings illustrate the potential potency of diimine ligands in photoactivatable Ru(ii) complexes.
Ligand-free Stille cross-coupling reaction using Pd/CaCO3 as catalyst reservoir
Coelho, Aline V.,de Souza, Andréa Luzia F.,de Lima, Paulo G.,Wardell, James L.,Antunes
, p. 7671 - 7674 (2007)
Stille reactions between halobenzenes and other substituted (hetero)arenes and tributylphenyltin were carried out in ethanol-water solution using Pd/CaCO3 as catalyst in a ligand-free system. The catalyst could be recycled three times without any loss of activity. The ethanol-water solution, after removal of the catalyst and extraction of the product, was found to have catalytic activity, thus showing the presence of soluble Pd(0)/Pd(II) species that can be regarded as the true catalysts.
Cationic tetra-and pentacoordinate complexes of nickel based on POCN-and POCOP-Type pincer ligands: Synthesis, characterization, and ligand exchange studies
Rahimi, Naser,Zargarian, Davit
supporting information, p. 15063 - 15073 (2021/09/04)
Stirring acetonitrile solutions of the charge-neutral pincer complexes (POCN)NiBr (1, POCN = κP,κC,κN-{2-(i-Pr)2PO,6-CH2{c-N(CH2)5}-C6H3) and (POCOP)NiBr (2, POCOP = κP,κC,κP′-2,6-(i-Pr2OP)2C6H3) with AgSbF6 facilitates Br- abstraction to give the corresponding cationic acetonitrile adducts [(POCN)Ni(NCMe)]+, 1a, and [(POCOP)Ni(NCMe)]+, 2a. Treating 1a and 2a with pyridine (py), 2,2′-bipyridine (bipy), phenanthroline (phen), or 4,4′-bipyridine (bipy?) gave the corresponding monocationic adducts [(POCN or POCOP)Ni(ligand)]+ (ligand = py: 1b and 2b; κN,κN′-bipy: 1c and 2c; κN,κN′-phen: 1d and 2d) and the dicationic dinuclear adducts [(POCN or POCOP)2Ni2(μ-bipy?)]2+ (1e and 2e). The new adducts 1a-1d and 2b-2e have been characterized by NMR spectroscopy; complex 1e proved to be insoluble and could not be analyzed by NMR. Single crystal X-ray diffraction studies were used to establish the solid-state structures of 1a-1e, and 2b-2d. UV-vis spectra have also been recorded for the pentacoordinated complexes 1c, 1d, 2c, and 2d. Studying the equilibria that govern the displacement of halides in (pincer)NiX (X = Cl, Br) by the in-coming nucleophiles py, bipy, and phen has allowed us to determine the following order for the relative nucleophilicities of the ligands involved in the halide substitution equilibria: Cl- > Br- > phen > bipy ? py > MeCN. Similar Keq measurements showed that cationic species are better stabilized with the POCN platform compared to POCOP. This implies that POCN is a better net donor of electron density compared to POCOP, such that the relative Lewis acidity (electrophilicity) of the cationic fragments should follow the order [(POCOP)Ni]+ > [(POCN)Ni]+. Cyclic voltammetry measurements on the bipy adducts showed reversible, one-electron oxidation events occurring at a lower value for [(POCN)Ni(bipy)]+, implying a more electron-rich Ni(ii) centre with POCN vs. POCOP. Consistent with these assertions, mixing (POCN)NiBr and [(POCOP)Ni(phen)]+ in acetonitrile gave [(POCN)Ni(phen)]+ and (POCOP)NiBr. Similarly, the Keq value of 0.19 for the equilibrium exchange (POCN)NiCl + (POCOP)NiBr ? (POCN)NiBr + (POCOP)NiCl indicates that the [(POCOP)Ni]+ fragment is better stabilized by Cl-vs. Br-. These exchange reactions do not occur in THF or CH2Cl2, implying that they are driven by the nucleophilic character of the solvent. This journal is
Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
supporting information, p. 2876 - 2894 (2021/02/01)
Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).