436857-75-9Relevant academic research and scientific papers
Mechanochemical routes for the synthesis of acetyl- A nd bis-(imino)pyridine ligands and organometallics
Shaw, Thomas E.,Shultz, Lorianne R.,Garayeva, Louiza R.,Blair, Richard G.,Noll, Bruce C.,Jurca, Titel
, p. 16876 - 16884 (2019/01/03)
Organometallic precatalysts play a pivotal role in organic synthesis. However, their preparation often relies on multiple time, energy, and solvent intensive steps, including the synthesis of supporting organic ligand structures, and finally installation
Radical mechanisms in the reaction of organic halides with diiminepyridine cobalt complexes
Zhu, Di,Korobkov, Ilia,Budzelaar, Peter H. M.
, p. 3958 - 3971 (2012/07/14)
The formally Co(0) complex LCo(N2) (L = 2,6-bis(2,6- dimethylphenyliminoethyl)pyridine) can be prepared via either Na/Hg reduction of LCoCl2 or hydrogenolysis of LCoCH2SiMe3. In the latter reaction, LCoH could be trapped by reaction with N≡CC 6H4-4-Cl to give LCoN=CHC6H4-4-Cl. LCo(N2) reacts with many alkyl and aryl halides RX, including aryl chlorides, to give a mixture of LCoR and LCoX in a halogen atom abstraction mechanism. Intermediacy of free alkyl and aryl radicals is confirmed by the ring-opening of cyclopropylmethyl to crotyl, and the rearrangement of 2,4,6-tBu3C6H2 to 3,5- tBu2C6H3CMe2CH 2, before binding to Co. The organocobalt species generated in this way react further with activated halides R′X (alkyl iodides; allyl and benzyl halides) to give cross-coupling products RR′ in what is most likely again a halogen abstraction mechanism. DFT studies support the proposed radical pathways for both steps. MeI couples smoothly with LCoCH2SiMe 3 to give LCoI and CH3CH2SiMe3, but the analogous reaction of tBuI leads in part to radical attack at the 3 and 4 positions of the pyridine ring to form (tBu 2-L)CoI and (tBu2-L)CoI2.
Synthesis and molecular and electronic structures of reduced bis(imino)pyridine cobalt dinitrogen complexes: Ligand versus metal reduction
Bowman, Amanda C.,Milsmann, Carsten,Atienza, Crisita Carmen Hojilla,Lobkovsky, Emil,Wieghardt, Karl,Chirik, Paul J.
, p. 1676 - 1684 (2010/04/02)
Sodium amalgam reduction of the aryl-substituted bis(imino)pyridine cobalt dihalide complexes (ArPDI)CoCl2 and (iPrBPDI) CoCl2 (ArPDI ) 2,6-(2,6-R2-C6H 3N=CMe)2C5H3N (R ) iPr, Et, Me); iPrBPDI ) 2,6-(2,6-iPr2-C 6H3N=CPh)2C5H3N) in the presence of an N2 atmosphere furnished the corresponding neutral cobalt dinitrogen complexes (ArPDI)CoN2 and ( iPrBPDI)CoN2. Magnetic measurements on these compounds establish doublet ground states. Two examples, (iPrPDI)CoN 2 and (iPrBPDI)CoN2, were characterized by X-ray diffraction and exhibit metrical parameters consistent with one-electron chelate reduction and a Co(I) oxidation state. Accordingly, the toluene solution EPR spectrum of (iPrPDI)CoN2 at 23 °C exhibits an isotropic signal with a g value of 2.003 and hyperfine coupling constant of 8 x 10-4 cm-1 to the I = 7/2 59Co center, suggesting a principally bis(imino)pyridine-based SOMO. Additional one-electron reduction of (iPrPDI)CoN2 was accomplished by treatment with Na[C10H8] in THF and yielded the cobalt dinitrogen anion [(iPrPDI)CoN2]-. DFT calculations on the series of cationic, neutral, and anionic bis(imino)pyridine cobalt dinitrogen compounds establish Co(I) centers in each case and a chelate-centered reduction in each of the sequential one-electron reduction steps. Frequency calculations successfully reproduce the experimentally determined N≡N infrared stretching frequencies and validate the computational methods. The electronic structures of the reduced cobalt dinitrogen complexes are evaluated in the broader context of bis(imino)pyridine base metal chemistry and the influence of the metal d electron configuration on the preference for closed-shell versus triplet diradical dianions.
Cobalt chloride complexes of N3 and N4 donor ligands
Kooistra, T. Martijn,Hekking, Koen F. W.,Knijnenburg, Quinten,De Bruin, Bas,Budzelaar, Peter H. M.,De Gelder, Rene,Smits, Jan M. M.,Gal, Anton W.
, p. 648 - 655 (2007/10/03)
A number of cobalt(II) chloride complexes of pyridine/amine N3 and N4 donors have been prepared and structurally characterised. Even though they are paramagnetic, assignment of the 1H NMR signals was possible in several cases. With the exception of tpa, which formed a cationic monochloride complex, all new complexes have cis-coordinated chlorides. Nevertheless, only the relatively rigid pyp ligands gave rise to (low) ethene polymerisation activity on activation with MAO. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Highly active iron and cobalt catalysts for the polymerization of ethylene [18]
Small,Brookhart,Bennett
, p. 4049 - 4050 (2008/10/08)
Using the previously examined Ni(II) and Pd(II) α-diimine catalysts as a guide, new iron(II) and cobalt(II) catalysts based on tridentate pyridine bis-mine ligands were prepared. The resulting catalysts are robust and extremely active for polymerization of ethylene to linear, high-density polyethylene.
