Rare‐Earth Metal Bis(dimethylsilyl)amide Complexes Supported by Cyclooctatetraenyl Ligands

Abstract

Monomeric cyclooctatetraenyl rare-earth metal complexes (COT)LnI(thf) 3 were examined by X-ray structure analysis for Ln = La and Sm being isostructural to the Nd and Ce congeners. Reaction of the lanthanum derivative with excess

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

“…10π‐Aromatic cyclooctatetraenyl (COT) ligands have played a key role in the organometallic chemistry of f‐elements for almost five decades . Following the discovery of the iconic uranocene, [U(COT) 2 ] in 1968, f‐element COT complexes of lanthanides (Ln) and actinides (An) have turned out to be a fascinating class of organometallic compounds featuring new types of metal–ligand interactions, and unusual molecular architectures .…”

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

“…There is a general understanding that the large, flat C 8 H 8 2À ring is ideally suited for overlapping with the f-orbitals of the large lanthanide and actinide ions. 2 Scheme 1 shows some prototypical lanthanide COT complexes which are considered milestones in the development of organolanthanide chemistry using COT ligands. 2 Scheme 1 shows some prototypical lanthanide COT complexes which are considered milestones in the development of organolanthanide chemistry using COT ligands.…”

“…11,12 Following the preparation of uranocene, other tetravalent actinidocenes An(C 8 H 8 ) 2 (Scheme 2; An = Th, Pa, Np, Pu) have also been reported. 13 In general, the use of the unsubstituted COT ligand in organolanthanide and -actinide chemistry has several disadvantages notable neutral lanthanide sandwich complex containing COT 00 is the cerocene derivative Ce(COT 00 ) 2 . Uranocene is also significantly more stable than cerocene and the thorium analogue Th(COT) 2 , which can be explained by a higher degree of covalency due to a stronger participation of the 5f and 6d orbitals in the uranium-cyclooctatetraenyl bonding.…”

The dinuclear scandium(III) cyclooctatetraenyl chloride complex di-μ-chlorido-bis[(η8-cyclooctatetraene)(tetrahydrofuran-κO)scandium(III)]

“…Interestingly, only one coordinated tetrahydrofuran (THF) molecule per dimer was found in the scandium product and that was related to the steric effect of the substituted COT ligands. In contrast to COT chloride products, the corresponding iodide complexes of lanthanides (Ce, Nd, Sm, and Tm) exhibit monomeric structures [see (B) in Scheme 1], with the number of coordinated THF molecules varying from 2 to 3 (Mashima & Takaya, 1989;Kilimann et al, 1994;Fedushkin et al, 2001;Meermann et al, 2009). Notably, only the lanthanum(III) COT iodide complex was found to exist in both monomeric and dimeric forms (Meermann et al, 2009).…”

“…In contrast to COT chloride products, the corresponding iodide complexes of lanthanides (Ce, Nd, Sm, and Tm) exhibit monomeric structures [see (B) in Scheme 1], with the number of coordinated THF molecules varying from 2 to 3 (Mashima & Takaya, 1989;Kilimann et al, 1994;Fedushkin et al, 2001;Meermann et al, 2009). Notably, only the lanthanum(III) COT iodide complex was found to exist in both monomeric and dimeric forms (Meermann et al, 2009). Herein we report the first X-ray diffraction characterization of the scandium(III) COT chloride complex [Sc(C 8 H 8 )Cl-(THF)] 2 , (1), and provide a structural comparison with the corresponding lanthanide series.…”