Unprecedented Bending and Rearrangement of f-Element Sandwich Complexes Induced by Superbulky Cyclooctatetraenide Ligands

The series of anionic lanthanide(III) sandwich complexes of the type [Ln(COT 00 ) 2 ] À (COT 00 = 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 00 ) 2 ] (Ln = Y (1), La (2), Pr (3), Gd (4), Tm (6), Lu (8)) and [Li(THF) 4 ][Ln(COT 00 ) 2 ] (Ln = Ho (5), Tm (7)) were prepared in good yields following a straightforward synthetic protocol which involves the treatment of LnCl 3 with 2 equiv. of in situprepared Li 2 COT 00 in either DME (=1,2-dimethoxyethane) or THF. The neutral actinide sandwich complexes An(COT 00 ) 2 (An = Th (9), U (10)) and An(COT 0 0 0 ) 2 (COT 0 0 0 = 1,3,6-tris(trimethylsilyl)cyclooctatetraenyl dianion; An = Th (11), U (12)) were synthesized in a similar manner, starting from ThCl 4 or UCl 4 , respectively. The COT 00 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 00 rings. Surprisingly, all six [Li(DME) 3 ][Ln(COT 00 ) 2 ] complexes covering the entire range of Ln 3+ ionic radii from La 3+ to Lu 3+ are isostructural (space group P % 1).Compound 10 is the first uranocene derivative for which 13 C NMR data are reported.

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“…respect to the uranium center. 30 The spectroscopic data of the complexes 9-12 are in good agreement with their structural features. 5).…”

Section: Resultssupporting

confidence: 59%

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

et al. 2015

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“…The lithium reagent was prepared following a literature protocol by metalation of 2,7‐bis(triphenylsilyl)cycloocta‐1,3,5‐triene with 2 equiv. of n ‐butyllithium . Subsequent reaction according to Scheme provided colorless crystals of the binuclear half‐sandwich complex [Li(DME) 3 ][Lu 2 (µ‐Cl) 3 (COT big ) 2 ] · DME ( 5 ) in 66 % yield.…”

Section: Resultsmentioning

confidence: 99%

“…All glassware was oven‐dried at 120 °C for at least 24 h, assembled while hot, and cooled under high vacuum prior to use. The starting materials, anhydrous LnCl 3 (Ln = Pr, Tb, Yb, Lu), 1,4‐C 8 H 6 (SiMe 3 ) 2 ,, and 1,4‐C 8 H 6 (SiPh 3 ) 2 , were prepared according to published procedures. The 1.6 m n ‐Butyllithium solution in hexanes and silver iodide were obtained from commercial sources and used as received.…”

Section: Methodsmentioning

confidence: 99%

“…In the last case, the corresponding Tb and Tm complexes did not show slow relaxation behavior. A new dimension in steric demand has been added to this chemistry through the introduction of the “superbulky“ ligand COT big [1,4‐bis(triphenylsilyl)cyclooctatetraenyl dianion] by us and the Evans group in 2011 . The use of COT big in organolanthanide and ‐actinide chemistry has led to unprecedented structural effects, such as the formation of a significantly bent anionic Ce III sandwich complex, a novel neutral cerocene formed by sterically induced SiPh 3 group migration, as well as the first example of a bent uranocene, [U(COT big ) 2 ], without additional donor ligands.…”

Section: Introductionmentioning

confidence: 99%

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Lanthanide(III) Sandwich and Half‐Sandwich Complexes with Bulky Cyclooctatetraenyl Ligands: Synthesis, Structures, and Magnetic Properties

et al. 2017

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Five new lanthanide(III) sandwich and half‐sandwich complexes with bulky cyclooctatetraenyl ligands have been prepared and fully characterized, including single‐crystal X‐ray structure determination. The treatment of anhydrous lanthanide(III) chlorides, LnCl3 (Ln = Pr, Tb, Yb), with 2 equivalents of Li2COT′′ [COT′′ = 1,4‐bis(trimethylsilyl)cyclooctatetraene dianion] followed by crystallization in the presence of a coordinating solvent afforded the anionic sandwich complexes [Li(THF)4][Pr(COT′′)2] (1), [Li(DME)3][Tb(COT′′)2] (2; DME = 1,2‐dimethoxyethane), and [Li(TMEDA)2][Yb(COT′′)2] (3; TMEDA = N,N,N′,N′‐tetramethylethylenediamine). Attempted oxidation of 2 with silver iodide did not afford the neutral terbium(IV) sandwich complex [Tb(COT′′)2]. Instead, the tri(µ‐iodido)‐bridged dinuclear half‐sandwich complex [Li(DME)2][Tb2(µ‐I)3(COT′′)2] (4) was isolated in 72 % yield. In this complex, the Li(DME)2 fragment is attached to one of the µ‐iodido ligands. A closely related binuclear lutetium complex, [Li(DME)3][Lu2(µ‐Cl)3(COTbig)2]·DME (5), was obtained by using the “superbulky“ COTbig ligand [COTbig = 1,4‐bis(triphenylsilyl)cyclooctatetraenyl dianion]. In addition to the spectroscopic and structural characterization, the magnetic properties of the paramagnetic terbium(III) derivative 2 have been investigated and further complemented by ab initio computational methods. These results have been used to discuss the structural requirements for potential terbium(III) single‐ion magnets.

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“…106 [ (Me 3 C) 3 C 5 H 2 ) 2 ThMe 2 ] reacts with [(Z 5 -1,2,4-(Me 3 C) 3 C 5 H 2 ) 2 Th(NH-p-tolyl) 2 ] to form the imide [(Z 5 -1,2,4-(Me 3 C) 3 C 5 H 2 ) 2 ThQN(p-tolyl)]; the product reacts with Ph 2 CQE (E = O, S) or CS 2 to afford [(Z 5 -1,2,4-(Me 3 C) 3 113 Owing to the bulkiness of the ring substituents, [U(COT BIG ) 2 ] is the first bis(cyclooctatetraenyl)uranium compound in which the rings are not parallel. 114 The reducible a-diimine ligand Mes …”

Section: Organometallicsmentioning

confidence: 99%

The actinides

Cotton

2012

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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Unprecedented Bending and Rearrangement of f-Element Sandwich Complexes Induced by Superbulky Cyclooctatetraenide Ligands

Cited by 40 publications

References 29 publications

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

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

Lanthanide(III) Sandwich and Half‐Sandwich Complexes with Bulky Cyclooctatetraenyl Ligands: Synthesis, Structures, and Magnetic Properties

The actinides

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