Syntheses and X-ray structures of cerium amide complexes

Reaction of CeCl3 with an excess of LiTMP (TMP-H = 2,2,6,6-tetramethylpiperidine) gave [Ce(mu-OCH=CH2)(TMP)(2)](2). The alkoxide ligand originated from THF, which was used as the solvent in the reaction. CeCl3 reacted with 3 equiv. of LiTMP in THF to produce, after crystallization, a 3:2 crystalline mixture of Ce(TMP)(3) and [Ce(mu-OCH=CH2)(TMP)(2)](2). Ce(TMP)(3) could not be isolated cleanly or separated from the mixture except by handpicking the crystals under a microscope. The homoleptic amide complex Ce[N-t-Bu(SiMe3)](3) was obtained by reacting CeCl3(THF)(2) with 3 equivalents of LiN-t-Bu(SiMe3). In the solid state, [Ce(mu-OCH=CH2)(TMP)(2)](2) is a dimer with a Ce(mu-OR)(2)Ce four-member ring, while Ce(TMP)(3) and Ce[N-t-Bu(SiMe3)](3) are trigonal planar monomers. There is structural evidence to suggest the presence of a Ce-vinyl group interaction in [Ce-(mu-OCH=CH2)(TMP)(2)](2). (c) 2005 Elsevier Ltd. All rights reserved.