Base-Free Lanthanoidocenes(II) Coordinated by Bulky Pentabenzylcyclopentadienyl Ligands

Abstract

Metalation of CpBn5H with PhCH2K (1:1 molar ratio) and subsequent reactions with 0.5 equiv of LnI2(THF) n (Ln = Yb, Sm, Eu, n = 2, 3) (THF, 30 °C, 1 h) afforded new lanthanoidocenes (CpBn5)2Ln (Ln = Yb (1), Sm (2), Eu (3)), which were isolated in reasonable yields. The X-ray diffraction studies revealed that the obtained complexes adopt the structures of bent sandwiches (CpCentr–Ln–CpCentr = 141.8–142.9°). Complexes 1–3 do not contain coordinated Lewis base molecules directly after recrystallization from toluene at ambient temperature; however they feature short contacts between Ln­(II) ions and o-carbon atoms of two pendant Ph groups. The reaction of equimolar amounts of YbI2(THF)2 and CpBn5K in DME afforded monocyclopentadienyl Yb­(II) complex [CpBn5Yb­(DME)­(μ-I)]2 (4). Complex 4 proved to be a centrosymmetric iodo-bridged dimer with trans-disposed cyclopentadienyl ligands, and no interactions of the Yb­(II) ion with pendant Ph groups were detected. Complexes 1–3 were inert toward Lewis bases (THF, DME, PMe3, TMEDA), small molecules (H2, SiH4, N2, CO), and molecules containing multiple C–C bonds (CH2CH2, PhCHCH2, trans-PhCHCHPh, cis-PhCHCHPh, CH2CH–CHCH2, Ph–CHCH–CHCH–Ph, PhCCPh, Me3SiCCSiMe3). Among compounds 1–3 only the samarium derivative 1 reacts with bipy and phenazine, affording SmIII complexes CpBn5 2Sm­(bipy–•) (5) and [(CpBn5)2Sm]2[μ-η3:η3-(C12H8N2)2–] (6). Complex 4 when illuminated with natural light undergoes redox reaction and in 72 h transforms into the mixed-valent compound {[CpBn5YbIIII2(μ-OMe)]2}2­{YbII(DME)3} (7), being a separated ion pair.

Deca-Arylsamarocene: An Unusually Inert Sm(II) Sandwich Complex

“…A paper from 2008 reports on the reaction of Cp* 2 Yb­(II) with tetra-(2-pyridyl)-substituted phenazine that formed a product in which a doubly reduced phenazine ligand is bridged by two Cp* 2 Yb­(III) + fragments . Although Trifonov’s (Bn 5 C 5 ) 2 Sm II hardly showed any reactivity with small molecules and unsaturated compounds, in reaction with phenazine the complex [(Bn 5 C 5 ) 2 Sm III ]­(phenazine), containing a doubly reduced phenazine 2– ion, was isolated . In strong contrast, reaction of 1 and phenazine at 110 °C for 24 h did not lead to any reaction and the starting material was obtained quantitatively.…”

“…The samarocene with bulky 1,2,4- t Bu 3 C 5 ligands was found to be slightly bent (167°), but in contrast to Cp* 2 Sm showed no reductive cleavage of alkyl isocyanides, and instead a simple monoadduct was isolated . Very recently, Trifonov and co-workers introduced the decabenzylsamarocene complex (Bn 5 C 5 ) 2 Sm, a complex that in the solid state is bent (141.8°) and in which two aromatic rings strongly coordinate to Sm. The latter Ph···Sm coordination is favored over metal interaction with polar ligands like THF, DME, TMEDA, or PMe 3 .…”

Single-Molecule Magnet Behavior in Dy3+ Half-Sandwich Complexes Based on Ene-Diamido and Cp* Ligands

“…The X-ray diffraction studies indicate that both compounds crystallize in the P 2 1 / c space group with a unique complex within the asymmetric unit (Figure , Table S1). Compound 1 is isostructural to the ytterbium complex we recently obtained . The coordination environments of the Dy 3+ in 1 and 2 are composed of one Cp* ligand, one dianionic 2σ:η 2 ene-diamido DAD 2– ligand and one coordinated THF molecule (for 1 ) or μ 2 -ClLi­(THF) 3 fragment (for 2 ).…”

Sandwich and Half-Sandwich Ln(II) (Ln = Sm, Yb) Complexes with Bulky Fluorenyl Ligands. Competitive Abstraction of H or SiMe3 from 2,7-tBu2-9-SiMe3-Fluorene by an Amido Anion

“…The Cp–Sm–Cp angles in 2b (127.9°), 3 (128.2°), and 6 (128.5°) are comparable to that in the related bis­(fluorenyl) compound ((C 13 H 9 ) 2 Sm­(THF) 2 126.4°), , while the Cp–Sm–Cp angle in 5 (138.0°) is close to those in (C 5 Me 5 ) 2 Sm­(THF) 2 (140.1°) and (C 5 Bn 5 ) 2 Sm (141.8°).…”