Base-Free Lanthanoidocenes(II) Coordinated by Bulky
Pentabenzylcyclopentadienyl Ligands
Alexander
N. Selikhov
Tatyana V. Mahrova
Anton V. Cherkasov
Georgy K. Fukin
Joulia Larionova
Jêrome Long
Alexander A. Trifonov
10.1021/acs.organomet.5b00243.s002
https://acs.figshare.com/articles/dataset/Base_Free_Lanthanoidocenes_II_Coordinated_by_Bulky_Pentabenzylcyclopentadienyl_Ligands/2164651
Metalation
of Cp<sup>Bn5</sup>H with PhCH<sub>2</sub>K (1:1 molar
ratio) and subsequent reactions with 0.5 equiv of LnI<sub>2</sub>(THF)<sub><i>n</i></sub> (Ln = Yb, Sm, Eu, <i>n</i> = 2,
3) (THF, 30 °C, 1 h) afforded new lanthanoidocenes (Cp<sup>Bn5</sup>)<sub>2</sub>Ln (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<sub>Centr</sub>–Ln–Cp<sub>Centr</sub> = 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 YbI<sub>2</sub>(THF)<sub>2</sub> and Cp<sup>Bn5</sup>K in DME afforded monocyclopentadienyl Yb(II) complex [Cp<sup>Bn5</sup>Yb(DME)(μ-I)]<sub>2</sub> (<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, PMe<sub>3</sub>, TMEDA), small molecules (H<sub>2</sub>, SiH<sub>4</sub>, N<sub>2</sub>, CO), and molecules containing multiple C–C bonds
(CH<sub>2</sub>CH<sub>2</sub>, PhCHCH<sub>2</sub>,
trans-PhCHCHPh, cis-PhCHCHPh, CH<sub>2</sub>CH–CHCH<sub>2</sub>, Ph–CHCH–CHCH–Ph, PhCCPh,
Me<sub>3</sub>SiCCSiMe<sub>3</sub>). Among compounds <b>1</b>–<b>3</b> only the samarium derivative <b>1</b> reacts with bipy and phenazine, affording Sm<sup>III</sup> complexes Cp<sup>Bn5</sup><sub>2</sub>Sm(bipy<sup>–•</sup>) (<b>5</b>) and [(Cp<sup>Bn5</sup>)<sub>2</sub>Sm]<sub>2</sub>[μ-η<sup>3</sup>:η<sup>3</sup>-(C<sub>12</sub>H<sub>8</sub>N<sub>2</sub>)<sup>2–</sup>] (<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<sup>Bn5</sup>Yb<sup>III</sup>I<sub>2</sub>(μ-OMe)]<sub>2</sub>}<sub>2</sub>{Yb<sup>II</sup>(DME)<sub>3</sub>} (<b>7</b>), being
a separated ion pair.
2015-05-26 00:00:00
TMEDA
72 h
0.5 equiv
2K
THF
DME
ambient temperature
Lewis base molecules
equimolar amounts
Bulky Pentabenzylcyclopentadienyl LigandsMetalation
pendant Ph groups
Lewis bases
CO
ion pair
1 h
CpBn 5K
CpBn 5H
Ln
redox reaction
CH
Yb