946848-29-9Relevant academic research and scientific papers
Bottom-Up Construction of a CO2-Based Cycle for the Photocarbonylation of Benzene, Promoted by a Rhodium(I) Pincer Complex
Anaby, Aviel,Feller, Moran,Ben-David, Yehoshoa,Leitus, Gregory,Diskin-Posner, Yael,Shimon, Linda J. W.,Milstein, David
, p. 9941 - 9950 (2016/08/19)
The use of carbon dioxide for synthetic applications presents a major goal in modern homogeneous catalysis. Rhodium-hydride PNP pincer complex 1 is shown to add CO2 in two disparate pathways: one is the expected insertion of CO2 into the metal-hydride bond, and the other leads to reductive cleavage of CO2, involving metal-ligand cooperation. The resultant rhodium-carbonyl complex was found to be photoactive, enabling the activation of benzene and formation of a new benzoyl complex. Organometallic intermediate species were observed and characterized by NMR spectroscopy and X-ray crystallography. Based on the series of individual transformations, a sequence for the photocarbonylation of benzene using CO2 as the feedstock was constructed and demonstrated for the production of benzaldehyde from benzene.
A dearomatized anionic PNP pincer rhodium complex: C-H and H-H bond activation by metal-ligand cooperation and inhibition by dinitrogen
Schwartsburd, Leonid,Iron, Mark A.,Konstantinovski, Leonid,Ben-Ari, Eyal,Milstein, David
, p. 2721 - 2729 (2011/07/30)
The anionic dearomatized complex [(PNP*)RhICl]K (2; PNP = 2,6-bis((di-tert-butylphosphino)methyl)pyridine, PNP* = deprotonated PNP) was prepared by reaction of the aromatic (PNP)RhICl complex 1 with KN(SiMe3)2 in dry benzene. Spectroscopic characterization and DFT calculations confirm a nonaromatic square-planar structure of complex 2. Under an atmosphere of dry argon, 2 undergoes facile C-H activation of benzene by cooperation between the metal center and the pincer ligand, with aromatization of the ligand, to form the complex (PNP)RhI(C 6H5) (3a). This reaction is inhibited by dinitrogen, which reacts with 2 to form the complex (PNP*)RhI(N2) (4), indicating higher stabilization of the 14-electron (PNP*)Rh I species 5 by dinitrogen as compared with chloride. Similarly, treatment of 2 with CO results in KCl liberation to form the dearomatized (PNP*)RhICO (8). In a protic environment, the dearomatized complex 2 is quickly reprotonated to regenerate the aromatic starting complex 1. Upon treatment with MeI, 2 undergoes oxidative addition to form the nonaromatic (PNP*)RhIII(CH3)Cl (10), while the dearomatized ligand remains intact. Complex 2 undergoes facile activation of H2 to form the monohydride (PNP)RhI(H) (11a) and with D2 to form (PNP)RhI(D) (11b) with benzylic-D incorporation, via metal-ligand cooperation by aromatization of the ligand. The reactivity of 2 with H2 is significantly higher than that of 4.
C-H bond activation by rhodium(I) phenoxide and acetate complexes: Mechanism of H-D exchange between arenes and water
Hanson, Susan Kloek,Heinekey, D. Michael,Goldberg, Karen I.
, p. 1454 - 1463 (2009/01/31)
New rhodium(I) complexes (PNP)Rh(X) (PNP = 2,6-bis(di-tert- butylphosphinomethyl)pyridine) (X = OTf(1), OAc (3), OH (8), OCH 2CF3 (9), OC6H5 (10), OC 6H4NO2 (11)) have been prepared. Hydroxide complex 8 and trifluoroethoxide complex 9 undergo stoichiometric activation of benzene-d6 to form the phenyl complex (PNP)Rh(C6D 5). Acetate and aryloxide complexes 3, 10, and 11 are active catalysts for H-D exchange between arenes and water. Control experiments indicate that the rhodium complexes are the active catalysts and that the observed exchange is not catalyzed by adventitious acid. Mechanistic studies of the H-D exchange reaction support a pathway involving dissociation of aryloxide or acetate ligand. The reaction is accelerated by added alcohol and, for the acetate complex, inhibited by added sodium acetate.
C-H bond activation by rhodium(I) hydroxide and phenoxide complexes
Kloek, Susan M.,Heinekey, D. Michael,Goldberg, Karen I.
, p. 4736 - 4738 (2008/02/10)
(Chemical Equation Presented) Rhodium(I) complexes of the form [(PNP)Rh(OR)] (R = H, CH2CF3, C6H5; PNP = 2,6-bis[(di-tert-butylphosphino)methyl]pyridine) have been prepared. Upon thermolysis in [D6]be
