Trivalent Cerium and Praseodymium Aromatic Ketone Adducts

Abstract

The reactions of the aromatic ketones benzophenone and 9‐fluorenone with trivalent [LnL3] complexes [Ln = Ce, Pr; L = N(SiMe3)2, C5H5 (Cp)] produce highly colored solutions in toluene. Characterization of these complexes by X‐ray diffraction revealed them to be monoadducts of the form [LnL3(ketone)]. The crystallographically determined C–O bonds of these complexes are longer than those of the free ketones. Significant ligand‐to‐metal charge transfer is also indicated by the ν(C=O) vibration of the coordinated ketone, which appears at lower wavelength. Solution‐based 1H NMR spectroscopy showed paramagnetic spectra of complexes Ln[N(SiMe3)2]3(ketone) and Ln(C5H5)3(ketone), which further supports this finding.

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2013

“…Significant ligand-to-metal charge transfer was also indicated by the (C O) vibrations of the coordinated ketones, which appeared at lower wavelength. 1 H NMR spectroscopy showed paramagnetic spectra of complexes Ln[N(SiMe 3 ) 2 ] 3 (ketone) and Cp 3 Ln(ketone), which further supported this finding [56].…”

Structure, Electronics and Reactivity of Ce(PNP) Complexes

“…We hypothesized that the addition of a strong O‐donor, such as Ph 2 C=O could lead the replacement of one of the P‐donor arms due to the oxophilic character of cerium . NMR monitoring of the benzene solution of 1 and benzophenone did not indicate shifts for the 1 H or 31 P NMR resonance, excluding the possibility of any donor exchange.…”

“…The Ce(1)ÀO(2) donor contacts (2.5749(17) and 2.5668(16) )a re noticeably longer than the relateds eparation measured in [Ce(N(SiMe 3 ) 2 ) 3 (Ph 2 C=O)] adduct (2.475 (1) ). [26] The bond distances between O(1) atom and Ce (1) (3) ). Newly formed C(27)ÀC(40) bonds measurea t1 .539(3) in both crystallographically independent molecules.…”

“…We hypothesized that the addition of as trong O-donor,s uch as Ph 2 C=Oc ould lead the replacement of one of the P-donor arms [22,25] due to the oxophilic charactero fc erium. [26] NMR monitoring of the benzene solution of 1 and benzophenone We postulated two possible reactionp athways of the C SiMe3 À Ha ctivation leading to the compound 6,n amely,p athways A and B (Scheme 5). In both pathways, the first step is the decoordination of one of the phosphorus arms [22,25] and the coordination of Ph 2 CO (intermediate 6a).…”

Reduction of Carbonyl Groups by Uranium(III) and Formation of a Stable Amide Radical Anion

“…Previously, [Sm II [N(SiMe 3 ) 2 ] 2 (THF) 2 ] has been demonstrated to reduce fluorenone and couple it to its pinacolate . Conversely, Ce III [N(SiMe 3 ) 2 ] 3 has been reacted with benzophenone and fluorenone without evidence of reduction . However, we reasoned that U III [N(SiMe 3 ) 2 ] 3 , which is able to reduce organic and inorganic azides, molecular oxygen, arenes, and other small molecules would also be reactive toward carbonyl functional groups.…”