Harmful:;123640-41-5Relevant articles and documents
Synthesis and electronic investigation of mono- and di-substituted 4-nitro- and 4-amino-pyrazol-1-yl bis(pyrazol-1-yl)pyridine-type ligands and luminescent Eu(III) derivatives
Strohecker,Lynch,Holliday,Jones
, p. 7733 - 7742 (2017)
Four new disubstituted and monosubstituted nitro- and amino- bis(pyrazol-1-yl)pyridine (bppy) ligands, substituted at the pyrazole 4-position (1, 2, 5, 6) have been synthesized, along with two luminescent Eu(iii) tris-β-diketonate derivatives of the amino
Redox-Induced Single-Molecule Magnetism in Mixed-Valent [2 × 2] Co4 Grid Complexes
Tong, Jin,Demeshko, Serhiy,John, Michael,Dechert, Sebastian,Meyer, Franc
, p. 4362 - 4372 (2016)
Homovalent [2 × 2] Co4 grid complexes [CoII4LH4](BF4)4 (1) and [CoII4LMe4](BF4)4 (2) with two new bis(terdentate) pyrazolate-bridged ligands, HLH = 3,5-bis(6-(1H-pyrazol-1-yl)pyrid-2-yl)pyrazole and HLMe = 4-methyl-3,5-bis(6-(1H-pyrazol-1-yl)pyrid-2-yl)pyrazole, were synthesized and comprehensively characterized. X-ray crystallographic analyses of 1 and 2 showed a square arrangement of cobalt(II) ions, each metal ion in distorted octahedral {N6} coordination created by two terdentate compartments from orthogonal ligand strands. Magnetic measurements revealed the metal ions high-spin (S = 3/2) state and moderate antiferromagnetic interactions to give an overall diamagnetic ST = 0 ground state of 1 and 2. Twofold oxidation, electrochemically or chemically, led to the dimixed-valent [2 × 2] Co4 grids [CoII2CoIII2LH4](BF4)6 (3) and [CoII2CoIII2LMe4](BF4)6 (4). ESI mass spectrometry confirmed the ruggedness of all grids 1-4 and their integrity in solution, and analysis of the UV/vis/NIR spectra suggested moderate electronic coupling. Solution 1H and 13C NMR spectra of paramagnetic 1-4 were recorded and confirmed that the dimixed-valent CoII2CoIII2 grids are charge-localized on the NMR time scale. X-ray crystallography revealed significant structural grid distortion upon oxidation, with the low-spin CoIII at opposite corners and in almost octahedral {N6} environment but the remaining CoII ions coordination sphere approaching a trigonal prism. SQUID studies showed the high-spin CoII to be magnetically isolated in the dimixed-valent CoII2CoIII2 grids, and both 3 and 4 to display frequency-dependent peaks in the out-of-phase (X′) component of the alternating-current (ac) magnetic susceptibility data, characteristic for single molecule magnet (SMM) properties (with energy barriers Ueff/kB = 16 and 26 K, and relaxation times 0 = 6.7·10-6 and 5.0·10-6 s for 3 and 4, respectively). The results are discussed in terms of cooperative effects that originate from elastic coupling within the grids, mediated by the rigid bridging ligands. These effects synergistically lead to the preferred trans configuration of the dimixed-valent CoII2CoIII2 grids and to structural distortions that are beneficial for SMM properties.
Palladium(II) pyrazolyl–pyridyl complexes containing a sterically hindered N-heterocyclic carbene moiety for the Suzuki-Miyaura cross-coupling reaction
Luconi, Lapo,Gafurov, Zufar,Rossin, Andrea,Tuci, Giulia,Sinyashin, Oleg,Yakhvarov, Dmitry,Giambastiani, Giuliano
, p. 100 - 105 (2018)
Cationic palladium complexes stabilized by a tridentate neutral {N,N,C} ligand containing a sterically hindered N-heterocyclic carbene (NHC) moiety have been prepared and characterized. The nature of the anionic counterion in the palladium complex has been varied to get crystals suitable for X-ray diffraction. The square planar structure of one of these complexes along with the axial contribution of the sterically hindered NHC fragment has been confirmed by X-ray analysis. In addition, all the isolated [{κ3-N,N,C}PdIICl]+X? [X? = Cl, PF6, BF4, B(C6H3Cl2)4] ion pairs have been scrutinized as catalysts in the cross-coupling Suzuki-Miyaura reaction between phenylboronic acid and variably substituted halo-aryl acceptors. Selected issues from this series have shown improved catalyst turn-over frequencies (TOFs) with respect to structurally related catalytic systems of the state-of-the-art.
Metal-free site-selective C-N bond-forming reaction of polyhalogenated pyridines and pyrimidines
Wang, Lei,Liu, Ning,Dai, Bin
, p. 82097 - 82111 (2015/10/12)
This paper presents a metal-free method for highly site-selective C-N bond-forming reaction of polyhalogenated pyridines and pyrimidines. The preferred coupling site can be tuned from the fluorine group bearing the N-heterocyclic ring to the chlorine group when changing from the pyridine ring to the pyrimidine ring. A wide array of halogenated pyridines preferentially reacted with amines at the fluorine group of the pyridine ring to generate monosubstituted halogenated pyridines with high selectivities. Different halogen atoms at various positions were produced by the pyridine ring that performed well under mild conditions. Halogenated pyrimidines underwent highly selective coupling at the chloride group with a wide range of amines having broad substrate applicability and moderate to good yields. The selectivity of the polyfluoropyridines in the developed reaction system was also tested, and the result indicated that the reaction occurred site-selectively at the ortho-position of the nitrogen ring. This reaction accommodated a wide range of halogenated groups. Thus, a wide range of chloro-, bromo-, iodo-, and fluoropyridines were generated, which have a wide utility for organic synthesis.
