87804-23-7Relevant articles and documents
Synthesis and structural elucidation of (pyridyl)imine Fe(II) complexes and their applications as catalysts in transfer hydrogenation of ketones
Tsaulwayo, Nokwanda,Kumah, Robert T.,Ojwach, Stephen O.
, (2021/01/25)
Reactions of (pyridyl)imine ligands: 2,6-diisopropyl-N-[(pyridine-2-yl)methylene]aniline (L1), 2,6-diisopropyl-N-[(pyridine-2-yl)ethylidene]aniline (L2), 2,6-dimethyl-N-[(pyridine-2-yl)methylene]aniline (L3), 2,6-dimethyl-N-[(pyridine-2-yl)ethylidene]aniline (L4) and N-[(pyridine-2-yl)methylene]aniline (L5) with FeCl2 salt afforded the corresponding paramagnetic Fe(II) complexes [Fe(L1)2Cl][FeCl4] (Fe1), [Fe(L2)2Cl][FeCl4] (Fe2), [Fe(L3)2Cl][FeCl4] (Fe3), [Fe(L4)2Cl][FeCl4], (Fe4), [Fe(L5)2Cl2] (Fe5) in good yields. On the other hand, reactions of L1 with FeCl2 in the presence of NaPF6 afforded complex [Fe(L1)2Cl][PF6] (Fe6) in moderate yields. Molecular structures of complexes Fe1 and Fe2 reveal the formation of cationic species containing two N^N bidentate ligands and one chlorido co-ligand to give five-coordinate geometry with [FeCl4]? as counter-anion. On the other hand, complex Fe5, is an octahedral neutral species containing two bidentate L5 and two chlorido ligands. All the complexes (Fe1–Fe6) formed active catalysts in the transfer hydrogenation of ketones affording average yields of about 85%. The ligand architecture, reaction conditions and nature of substrate influenced the catalytic activities of the complexes. Mercury and subs-stoichiometric poisoning tests pointed to the existence of both Fe(0) nanoparticles and homogeneous Fe(II) species as the active intermediates.
Synthesis and Applications of (Pyridyl)imine Fe(II) Complexes as Catalysts in Transfer Hydrogenation of Ketones
Kumah, Robert T.,Vijayan, Paranthaman,Ojwach, Stephen O.
, p. 344 - 352 (2020/07/25)
Abstract: Chiral (pyridyl)imine Fe(II) complexes, [Fe(L1)3]2+[PF6?]2, (Fe1), [Fe(L2)3]2+[PF6?]2, (Fe2), [Fe(L3)3]2+[PF6?]2 (Fe3), and [Fe(L4)3]2+[PF6?]2 (Fe4) were synthesised by reactions of synthons (S-)-1-phenyl-N-(pyridine-2-yl) ethylidine)ethanamine (L1), (R-)-1-phenyl-N-(pyridine-2-yl) ethylidine) ethanamine (L2), (S)-1-phenyl-N-(pyridine-2-yl methylene) ethanamine (L3) and (S)-1-phenyl-N-(pyridine-2-yl methylene)ethanamine (L4) with the FeCl2 salt. The solid-state structure of complex Fe4 showed that the?Fe atom contains three units of bidentate bound ligand L4 to form a six-coordinate cationic compound. The Fe(II) complexes were evaluated as catalysts in asymmetric transfer hydrogenation of ketones reactions and showed moderate catalytic activities with low enantioselectivity. Catalytic activities of the respective complexes were regulated by the nature of the metal complexes, ketone substrate and reaction conditions. Mercury and sub-stoichiometric poisoning experiments implicate possible formation of both active Fe(0) nanoparticles and Fe(II) homogeneous intermediates. Graphic Abstract: [Figure not available: see fulltext.]
Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
Mukherjee, Aparajita,Bhattacharya, Samaresh
, p. 15617 - 15631 (2021/05/19)
The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
