title: Synthesis and structural diversity of trivalent rare-earth metal diisopropylamide complexes.
abstract: A series of rare-earth metal diisopropylamide complexes has been obtained via salt metathesis employing LnCl3(THF)x and lithium (LDA) or sodium diisopropylamide (NDA) in n-hexane. Reactions with AM : Ln ratios ≥3 gave ate complexes (AM)Ln(NiPr2)4(THF)n (n = 1, 2; Ln = Sc, Y, La, Lu; AM = Li, Na) in good yields. For smaller rare-earth metal centres such as scandium and lutetium, a Li : Ln ratio = 2.5 accomplished ate-free tris(amido) complexes Ln(NiPr2)3(THF). The chloro-bridged dimeric derivatives [Ln(NiPr2)2(μ-Cl)(THF)]2 (Ln = Sc, Y, La, Lu) could be obtained in high yields for Li : Ln = 1.6-2. The product resulting from the Li : La = 1 : 1.6 reaction revealed a crystal structure containing two different molecules in the crystal lattice, [La(NiPr2)2(THF)(μ-Cl)]2·La(NiPr2)3(THF)2. Recrystallization of the chloro-bridged dimers led to the formation of the monomeric species Ln(NiPr2)2Cl(THF)2 (Ln = Sc, Lu) and La(NiPr2)3(THF)2. The reaction of YCl3 and LDA with Li : Y = 2 in the absence of THF gave a bimetallic ate complex LiY(NiPr2)4 with a chain-like structure. For scandium, the equimolar reactions with LDA or NDA yielded crystals of tetrametallic mono(amido) species, {[Sc(NiPr2)Cl2(THF)]2(LiCl)}2 and [Sc(NiPr2)Cl2(THF)]4, respectively. Depending on the Ln(iii) size, AM, and presence of a donor solvent, ate complexes (AM)Ln(NiPr2)4(THF)n show distinct dynamic behaviour as revealed by variable temperature NMR spectroscopy. The presence of weak LnCH(iPr) β-agostic interactions, as indicated by Ln-N-C angles <105°, is corroborated by DFT calculations and NBO analysis.
authors.affiliation: Institut für Anorganische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. reiner.anwander@uni-tuebingen.de peter.sirsch@uni-tuebingen.de.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Spallek
authors.forename: Oliver
authors.initials: O
authors.lastname: Heß
authors.forename: Melanie
authors.initials: M
authors.lastname: Meermann-Zimmermann
authors.forename: Christian
authors.initials: C
authors.lastname: Meermann
authors.forename: Michael G
authors.initials: MG
authors.lastname: Klimpel
authors.forename: Frank
authors.initials: F
authors.lastname: Estler
authors.forename: David
authors.initials: D
authors.lastname: Schneider
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Scherer
authors.forename: Maxim
authors.initials: M
authors.lastname: Tafipolsky
authors.forename: Karl W
authors.initials: KW
authors.lastname: Törnroos
authors.forename: Cäcilia
authors.initials: C
authors.lastname: Maichle-Mössmer
authors.forename: Peter
authors.initials: P
authors.lastname: Sirsch
authors.forename: Reiner
authors.initials: R
authors.lastname: Anwander