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

Metalation of Cp^Bn5H with PhCH₂K (1:1 molar ratio) and subsequent reactions with 0.5 equiv of LnI₂(THF)_<i>n</i> (Ln = Yb, Sm, Eu, <i>n</i> = 2, 3) (THF, 30 °C, 1 h) afforded new lanthanoidocenes (Cp^Bn5)₂Ln (Ln = Yb (<b>1</b>), Sm (<b>2</b>), Eu (<b>3</b>)), which were isolated in reasonable yields. The X-ray diffraction studies revealed that the obtained complexes adopt the structures of bent sandwiches (Cp_Centr–Ln–Cp_Centr = 141.8–142.9°). Complexes <b>1</b>–<b>3</b> 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 <i>o</i>-carbon atoms of two pendant Ph groups. The reaction of equimolar amounts of YbI₂(THF)₂ and Cp^Bn5K in DME afforded monocyclopentadienyl Yb­(II) complex [Cp^Bn5Yb­(DME)­(μ-I)]₂ (<b>4</b>). Complex <b>4</b> 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 <b>1</b>–<b>3</b> 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 <b>1</b>–<b>3</b> only the samarium derivative <b>1</b> reacts with bipy and phenazine, affording Sm^III complexes Cp^Bn5₂Sm­(bipy^–•) (<b>5</b>) and [(Cp^Bn5)₂Sm]₂[μ-η³:η³-(C₁₂H₈N₂)^2–] (<b>6</b>). Complex <b>4</b> when illuminated with natural light undergoes redox reaction and in 72 h transforms into the mixed-valent compound {[Cp^Bn5Yb^IIII₂(μ-OMe)]₂}₂­{Yb^II(DME)₃} (<b>7</b>), being a separated ion pair

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

Metalation of Cp^Bn5H with PhCH₂K (1:1 molar ratio) and subsequent reactions with 0.5 equiv of LnI₂(THF)_<i>n</i> (Ln = Yb, Sm, Eu, <i>n</i> = 2, 3) (THF, 30 °C, 1 h) afforded new lanthanoidocenes (Cp^Bn5)₂Ln (Ln = Yb (<b>1</b>), Sm (<b>2</b>), Eu (<b>3</b>)), which were isolated in reasonable yields. The X-ray diffraction studies revealed that the obtained complexes adopt the structures of bent sandwiches (Cp_Centr–Ln–Cp_Centr = 141.8–142.9°). Complexes <b>1</b>–<b>3</b> 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 <i>o</i>-carbon atoms of two pendant Ph groups. The reaction of equimolar amounts of YbI₂(THF)₂ and Cp^Bn5K in DME afforded monocyclopentadienyl Yb­(II) complex [Cp^Bn5Yb­(DME)­(μ-I)]₂ (<b>4</b>). Complex <b>4</b> 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 <b>1</b>–<b>3</b> 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 <b>1</b>–<b>3</b> only the samarium derivative <b>1</b> reacts with bipy and phenazine, affording Sm^III complexes Cp^Bn5₂Sm­(bipy^–•) (<b>5</b>) and [(Cp^Bn5)₂Sm]₂[μ-η³:η³-(C₁₂H₈N₂)^2–] (<b>6</b>). Complex <b>4</b> when illuminated with natural light undergoes redox reaction and in 72 h transforms into the mixed-valent compound {[Cp^Bn5Yb^IIII₂(μ-OMe)]₂}₂­{Yb^II(DME)₃} (<b>7</b>), being a separated ion pair

Yb(II) Triple-Decker Complex with the μ‑Bridging Naphthalene Dianion [Cp^Bn5Yb(DME)]₂(μ‑η⁴:η⁴‑C₁₀H₈). Oxidative Substitution of [C₁₀H₈]^2– by 1,4-Diphenylbuta-1,3-diene and P₄ and Protonolysis of the Yb–C₁₀H₈ Bond by PhPH₂

Two synthetic approaches to the new three-decker Yb­(II) complex [Cp^Bn5Yb­(DME)]₂[μ-C₁₀H₈] (<b>1</b>) were successfully employed: the reaction of [Cp^Bn5Yb­(DME)­(μ-I)]₂ (<b>2</b>) with 2 molar equiv of [C₁₀H₈]⁻·K in DME and the reaction of [YbI­(DME)₂]₂[μ-C₁₀H₈] (<b>3</b>) with Cp^Bn5K in a 1:2 molar ratio in DME. Complex <b>1</b> was proved to be a Yb­(II) binuclear triple-decker complex containing a dianionic naphthalene ligand bridging two Cp^Bn5Yb­(DME) fragments in a μ-η⁴:η⁴ fashion. An oxidative substitution of (C₁₀H₈)^2– by <i>trans</i>-(1<i>E</i>,3<i>E</i>)-1,4-diphenylbuta-1,3-diene afforded the three-decker Yb­(II) complex [Cp^Bn5Yb­(DME)]₂(μ-η⁴:η⁴ -PhCHCHCHCHPh) (<b>4</b>) with a dianionic μ-η⁴:η⁴-bridging diphenylbutadiene ligand and naphthalene. The reaction of <b>1</b> with excess P₄ also occurs with oxidation of (C₁₀H₈)^2–, whereas Yb remains divalent. The reaction results in the formation of the trinuclear Yb­(II) complex with a μ-bridging P₇^3– ligand [Cp^Bn5Yb­(DME)]₃(P₇) (<b>5</b>). Protonation of the Yb–C₁₀H₈ bond in <b>1</b> with PhPH₂ (1:2 molar ratio) afforded the dimeric phosphido complex [Cp^Bn5Yb­(THF)­(μ₂-PHPh)]₂ (<b>6</b>) in 64% yield, while an attempt to obtain a phosphinidene Yb­(II) species by reacting equimolar amounts of <b>1</b> and PhPH₂ in DME resulted in the isolation of the metallocene complex Cp^Bn5₂Yb­(DME) (<b>7</b>)

Yb(II) Triple-Decker Complex with the μ‑Bridging Naphthalene Dianion [Cp^Bn5Yb(DME)]₂(μ‑η⁴:η⁴‑C₁₀H₈). Oxidative Substitution of [C₁₀H₈]^2– by 1,4-Diphenylbuta-1,3-diene and P₄ and Protonolysis of the Yb–C₁₀H₈ Bond by PhPH₂

Two synthetic approaches to the new three-decker Yb­(II) complex [Cp^Bn5Yb­(DME)]₂[μ-C₁₀H₈] (<b>1</b>) were successfully employed: the reaction of [Cp^Bn5Yb­(DME)­(μ-I)]₂ (<b>2</b>) with 2 molar equiv of [C₁₀H₈]⁻·K in DME and the reaction of [YbI­(DME)₂]₂[μ-C₁₀H₈] (<b>3</b>) with Cp^Bn5K in a 1:2 molar ratio in DME. Complex <b>1</b> was proved to be a Yb­(II) binuclear triple-decker complex containing a dianionic naphthalene ligand bridging two Cp^Bn5Yb­(DME) fragments in a μ-η⁴:η⁴ fashion. An oxidative substitution of (C₁₀H₈)^2– by <i>trans</i>-(1<i>E</i>,3<i>E</i>)-1,4-diphenylbuta-1,3-diene afforded the three-decker Yb­(II) complex [Cp^Bn5Yb­(DME)]₂(μ-η⁴:η⁴ -PhCHCHCHCHPh) (<b>4</b>) with a dianionic μ-η⁴:η⁴-bridging diphenylbutadiene ligand and naphthalene. The reaction of <b>1</b> with excess P₄ also occurs with oxidation of (C₁₀H₈)^2–, whereas Yb remains divalent. The reaction results in the formation of the trinuclear Yb­(II) complex with a μ-bridging P₇^3– ligand [Cp^Bn5Yb­(DME)]₃(P₇) (<b>5</b>). Protonation of the Yb–C₁₀H₈ bond in <b>1</b> with PhPH₂ (1:2 molar ratio) afforded the dimeric phosphido complex [Cp^Bn5Yb­(THF)­(μ₂-PHPh)]₂ (<b>6</b>) in 64% yield, while an attempt to obtain a phosphinidene Yb­(II) species by reacting equimolar amounts of <b>1</b> and PhPH₂ in DME resulted in the isolation of the metallocene complex Cp^Bn5₂Yb­(DME) (<b>7</b>)

Yb(II) Triple-Decker Complex with the μ‑Bridging Naphthalene Dianion [Cp^Bn5Yb(DME)]₂(μ‑η⁴:η⁴‑C₁₀H₈). Oxidative Substitution of [C₁₀H₈]^2– by 1,4-Diphenylbuta-1,3-diene and P₄ and Protonolysis of the Yb–C₁₀H₈ Bond by PhPH₂

Two synthetic approaches to the new three-decker Yb­(II) complex [Cp^Bn5Yb­(DME)]₂[μ-C₁₀H₈] (<b>1</b>) were successfully employed: the reaction of [Cp^Bn5Yb­(DME)­(μ-I)]₂ (<b>2</b>) with 2 molar equiv of [C₁₀H₈]⁻·K in DME and the reaction of [YbI­(DME)₂]₂[μ-C₁₀H₈] (<b>3</b>) with Cp^Bn5K in a 1:2 molar ratio in DME. Complex <b>1</b> was proved to be a Yb­(II) binuclear triple-decker complex containing a dianionic naphthalene ligand bridging two Cp^Bn5Yb­(DME) fragments in a μ-η⁴:η⁴ fashion. An oxidative substitution of (C₁₀H₈)^2– by <i>trans</i>-(1<i>E</i>,3<i>E</i>)-1,4-diphenylbuta-1,3-diene afforded the three-decker Yb­(II) complex [Cp^Bn5Yb­(DME)]₂(μ-η⁴:η⁴ -PhCHCHCHCHPh) (<b>4</b>) with a dianionic μ-η⁴:η⁴-bridging diphenylbutadiene ligand and naphthalene. The reaction of <b>1</b> with excess P₄ also occurs with oxidation of (C₁₀H₈)^2–, whereas Yb remains divalent. The reaction results in the formation of the trinuclear Yb­(II) complex with a μ-bridging P₇^3– ligand [Cp^Bn5Yb­(DME)]₃(P₇) (<b>5</b>). Protonation of the Yb–C₁₀H₈ bond in <b>1</b> with PhPH₂ (1:2 molar ratio) afforded the dimeric phosphido complex [Cp^Bn5Yb­(THF)­(μ₂-PHPh)]₂ (<b>6</b>) in 64% yield, while an attempt to obtain a phosphinidene Yb­(II) species by reacting equimolar amounts of <b>1</b> and PhPH₂ in DME resulted in the isolation of the metallocene complex Cp^Bn5₂Yb­(DME) (<b>7</b>)