Issue 10, 2015

One ligand fits all: lanthanide and actinide sandwich complexes comprising the 1,4-bis(trimethylsilyl)cyclooctatetraenyl (=COT′′) ligand

Abstract

The series of anionic lanthanide(III) sandwich complexes of the type [Ln(COT′′)2] (COT′′ = 1,4-bis(trimethylsilyl)cyclooctatetraenyl dianion) has been largely extended by the synthesis of eight new derivatives ranging from lanthanum to lutetium. The new compounds [Li(DME)3][Ln(COT′′)2] (Ln = Y (1), La (2), Pr (3), Gd (4), Tm (6), Lu (8)) and [Li(THF)4][Ln(COT′′)2] (Ln = Ho (5), Tm (7)) were prepared in good yields following a straightforward synthetic protocol which involves the treatment of LnCl3 with 2 equiv. of in situ-prepared Li2COT′′ in either DME (=1,2-dimethoxyethane) or THF. The neutral actinide sandwich complexes An(COT′′)2 (An = Th (9), U (10)) and An(COT′′′)2 (COT′′′ = 1,3,6-tris(trimethylsilyl)cyclooctatetraenyl dianion; An = Th (11), U (12)) were synthesized in a similar manner, starting from ThCl4 or UCl4, respectively. The COT′′ ligand imparts excellent solubility even in low-polar solvents as well as excellent crystallinity to all new compounds studied. All twelve new f-element sandwich complexes have been structurally authenticated by single-crystal X-ray diffraction. All are nearly perfect sandwich complexes with little deviation from the coplanar arrangement of the substituted COT′′ rings. Surprisingly, all six [Li(DME)3][Ln(COT′′)2] complexes covering the entire range of Ln3+ ionic radii from La3+ to Lu3+ are isostructural (space group P[1 with combining macron]). Compound 10 is the first uranocene derivative for which 13C NMR data are reported.

Graphical abstract: One ligand fits all: lanthanide and actinide sandwich complexes comprising the 1,4-bis(trimethylsilyl)cyclooctatetraenyl (=COT′′) ligand

Supplementary files

Article information

Article type
Paper
Submitted
21 Apr 2015
Accepted
03 Jun 2015
First published
04 Jun 2015
This article is Open Access
Creative Commons BY license

New J. Chem., 2015,39, 7656-7666

Author version available

One ligand fits all: lanthanide and actinide sandwich complexes comprising the 1,4-bis(trimethylsilyl)cyclooctatetraenyl (=COT′′) ligand

J. Rausch, C. Apostolidis, O. Walter, V. Lorenz, C. G. Hrib, L. Hilfert, M. Kühling, S. Busse and F. T. Edelmann, New J. Chem., 2015, 39, 7656 DOI: 10.1039/C5NJ00991J

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