TY - JOUR
T1 - A dearomatized anionic PNP pincer rhodium complex
T2 - C-H and H-H bond activation by metal-ligand cooperation and inhibition by dinitrogen
AU - Schwartsburd, Leonid
AU - Iron, Mark A.
AU - Konstantinovski, Leonid
AU - Ben-Ari, Eyal
AU - Milstein, David
PY - 2011/5/23
Y1 - 2011/5/23
N2 - 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.
AB - 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.
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U2 - 10.1021/om200104b
DO - 10.1021/om200104b
M3 - Article
AN - SCOPUS:79956092608
VL - 30
SP - 2721
EP - 2729
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 10
ER -