Lanthanide(III) complexes with cyclooctatetraene dianion. Synthetic chemistry, characterization, and physical properties

Abstract

This paper reports two series of lanthanide -carbocydic complexes of formula K[Ln(C8Hs)2] and [Ln(C8H8)Cl • 2C4H80]2. Single crystal X-ray structures of the cerium member of both series have been previously determined. Analytical and spectral data strongly suggest that the other lanthanide complexes in each series are isostructural with the cerium complexes. Chemical and spectral data show that these lanthanide cyclooctatetraenyl metallocenes are highly ionic relative to the analogous actinide complexes. This trend undoubtedly results from the inability of the lanthanide 4f orbitals to contribute to covalent bonding relative to the 5f orbitals. Similar properties are found for the corresponding complex with yttrium, a metal which is not a lanthanide rare earth. Using (17) F.

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

“…1a (La) Ce [9] 1b (Nd) [b] 1c (Sm) Tm [42] 2 (La) The latter heteroleptic chloride species were synthesized for differently sized rare-earth metal centers, including yttrium. [43][44][45] Mixed COT/iodide compounds of the smaller rare-earth metal centers are still lacking, except (COT)-TmI(thf) 2 (route III, Scheme 1). [42] Crucially, route I is not applicable for the synthesis of (COT)LnI(thf) n of smaller rare-earth metals such as yttrium because of the reduced reactivity of such Ln metals, even under harsher conditions (high temperature/pressure tube and/or sonication).…”

Generation and electronic properties of lanthanide–cyclooctatetraene organometallic clusters in gas phase

“…Therefore, organolanthanide compounds have long been assumed to be optical, and magnetic materials for such 4f orbitals are shielded largely from external interactions by the outer 5s and 5p orbitals [2,3]. Numerous experimentalists and theoreticians have been prompted to describe the bonding of organolanthanide compounds as wholly ionic [4][5][6][7]. In the condensed phase, the alkali metal salts are generally prepared as M alkali + [Ln 3+ (C 8 H 2− 8 ) 2 ].…”

Relativistic and Electron-Correlation Effects in the Ground States of Lanthanocenes and Actinocenes

“…Why is cerocene the only neutral lanthanocene known experimentally, whereas the corresponding salts of the anionic lanthanocenes, such as K[Ln(C 8 H 8 ) 2 ], are well-known even for the heavier lanthanides? [13,21] Why does thorocene, despite the fact that it is stable, obviously not form a corresponding anion, in contrast to cerocene? If the cerocene is indeed bis ([8]annulene)cerium(iii), whereas thorocene is rather bis ([8]annulene)thorium(iv), what about the situation at the end of both series?…”