Lanthanocene Chemistry with [Cp^R]^-, [Cp^t]^-, [Cp^tt]^-, and [Cp^R‘₂SiMe₂]^2-Ligands:  Synthesis and Characterization of Bis(cyclopentadienyl)lanthanide(III) Halides and Bis(cyclopentadienyl)lanthanide(II) Complexes and Crystal Structures of [{NdCp^R₂(μ-Cl)}₂], [{TmCp^tt₂(μ-I)}₂], and [Yb(Cp^R‘

Abstract

The bis(substituted cyclopentadienyl)lanthanide(III) halides [{LnCp R 2 (µ-Cl)} 2 ] (Ln ) Pr, Nd, Sm, Dy, Tb, Y), [{LnCp tt 2 (µ-X)} 2 ] (X ) Cl, Ln ) La, Nd; X ) I, Ln ) Tm), and [Nd-) have been synthesized from the appropriate LnCl 3 , TmI 3 , or LnI 2 with the selected sodium or potassium cyclopentadienide. The complexes were characterized by 1 H, 13 C, 29 Si, and 171 Yb (for Yb(II) complexes) NMR spectroscopy, elemental analysis, and mass spectrometry. The molecular structures of [{NdCp R 2 (µ-Cl)} 2 ], [{TmCp tt 2 (µ-I)} 2 ], and [Yb(Cp R′ 2 -SiMe 2 )(THF) 2 ] have been determined by single-crystal X-ray diffraction studies. Attempts to reduce the complexes [{NdCp R 2 (µ-Cl)} 2 ], [{NdCp tt 2 (µ-Cl)} 2 ], and [{TmCp tt 2 (µ-I)} 2 ] are described.Supporting Information Available: Tables of X-ray crystallographic data for 2, 9, and 23. This material is available free of charge via the Internet at http://pubs.acs.org. Crystallographic data for the structural analyses have also been deposited with the Cambridge Crystallographic Data Center. Copies of the information can be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K.

Bond-valence parameters of lanthanides

“…The oxidation state of the metal atom is not specified in many of the compounds available in the CSD [especially with regard to oxidation state +2, e.g. CSD refcode ZOGKOV (Abrahams et al, 1995), BEVXUW (Harder, 2004), XATWOE (Rabe et al, 2000), TEYVIC (Rogers, 1996), RADJIP (Hitchcock et al, 2000), CUWGEG (Evans, Grate et al, 1985)] or the oxidation state is incorrectly assigned. For example, in the CSD the central ion may be assigned as divalent, whereas in the original work it is correctly assigned as trivalent [CSD refcode SMNICD (Moore et al, 1972), KADKEG (Woodman et al, 2003), CUGPEZ (Deacon et al, 1984), EGIMUC (Chen et al, 2002)].…”

Synthesis of a new stable, neutral organothulium(ii) complex by reduction of a thulium(iii) precursor

“…However, earlier attempts at the synthesis of neutral cyclopentadienyl complexes of Ln II (Ln = Nd, Tm) by this latter route have proven unsuccessful, although Ln II species seemed to be involved at early stages of the reaction. In these attempts, polar solvents such as THF 4 or DME 5 were used. Since decomposition of ''nonclassical'' divalent organolanthanides proceeds via electron transfer to the coordinated solvent, we reasoned that non-polar solvents would constitute a better reaction medium for the access to Ln II complexes by reduction of Ln III precursors.…”

“…The most noteworthy feature is the monomeric nature of this complex in the solid state. The other known bis(cyclopentadienyl)thulium(III) iodides are either a m-iodo dimer, 4 or solvated 9 or chelated 5,10 monomers. The recently reported (Cp ttt ) 2 CeF, a related halide complex of Ce III with Cp ttt , is also monomeric in the solid state.…”

Mixed Disilyl‐Substituted Cyclopentadiene Derivatives and Corresponding Zirconium, Molybdenum and Tungsten Compounds

“…While several chelating mixed disilylcyclopentadienyl ancillary ligands are known, [5,15,19] reports of nonbridged disubstituted cyclopentadienyl metal compounds with different organonosilyl substituents at the aromatic ring are scarce. [20] Within this context, we were interested in the synthesis of mixed disilylcyclopentadienyl metal compounds through the introduction of different alkyl, alkenyl or alkynyl substituents into the silyl units of the cyclopentadiene system to test the chemical and structural properties of corresponding transition-metal cyclopentadienyl compounds.…”