Donor-Solvent-Dependent Cluster Formation of (C₅Me₅)SmI₂(THF)_x-Type Half-Sandwich Complexes

Abstract

In this study, we demonstrate the structural variety of the Cp*SmI y system with respect to the amount of donor molecules (THF) present. The reaction of SmI2(THF)2 with 0.5 equiv of bis­(pentamethyl­cyclopentadienyl)­lead­(II), PbCp*2, in THF gives the highly solvated monomeric complex Cp*SmI2(THF)3, when crystallized from THF. The same reaction performed in n-hexane followed by crystallization from toluene gave the partially solvated trimetallic complex [Cp*3Sm3I­(μ2-I)3­(μ3-I)2(THF)2]. Recrystallization of the Sm3 cluster from either C6D6 at ambient temperature or toluene at −40 °C produced the tetrametallic complex [Cp*4Sm4I­(μ2-I)4­(μ3-I)2(μ4-I)­(THF)]. Reaction of SmI2, obtained via treatment of SmI2(THF)2 with excess AlEt3 in n-pentane, with 0.5 equiv of PbCp*2 in toluene led to the donor-free mixed-valent pentametallic complex [Cp*5Sm5(μ2-I)4­(μ3-I)4(μ5-I)]. All compounds were characterized by single-crystal X-ray structure analysis.

Lanthanide(III) Sandwich and Half‐Sandwich Complexes with Bulky Cyclooctatetraenyl Ligands: Synthesis, Structures, and Magnetic Properties

“…Literature data on structurally characterized Tb–I complexes are exceptionally scarce, and to the best of our knowledge compound 4 represents the first molecular Tb compound with µ‐bridging I – ligands. The Tb–I–Tb angles [81.76(1) and 81.99(1)°] are comparatively small in view of the Ln–I–Ln angles observed in other lanthanide complexes, for example, [La 2 (µ‐I) 2 I 2 {HC(Ph 2 P=NSiMe 3 ) 2 } 2 ] [La–I–La 101.70(2)°] and [Sm 3 (µ 3 ‐I)(µ‐I) 3 ICp* 3 (THF) 2 ] [Sm–I–Sm 89.9(5)–93.0(4)°] . The lithium atom in 4 exhibits a well‐defined trigonal‐bipyramidal [4+1] coordination with O2 and O2′ defining the axial positions [O2–Li–O2′ 177.9(7)°, O2–Li ··· I1 89.0(3)°, angle sum within the O1O1′I1 plane 360.1(4)°].…”

Lewis‐Acid Stabilized Organoimide Complexes of Divalent Samarium, Europium, and Ytterbium

“…This redox protocol has already proven viable for the efficient synthesis of homoleptic Cp* 3 Sm and [C 5 H 3 (SiMe 3 ) 2 ] 3 Yb, both prepared from the corresponding divalent sandwich complexes and the respective plumbocene derivative. Only recently we have shown that lanthanide half‐sandwich and sandwich complexes (Ln=Sm, Eu, Yb) coordinated by alkyl, halide, silylamido, and pyrazolato ligands can be synthesized by redox transmetallation with the plumbocene derivative Cp* 2 Pb . Herein, the applicability of this elegant route in oxidation reactions with Ln II imides was probed.…”

“…Only recently we have shown that lanthanide halfsandwichand sandwich complexes (Ln = Sm, Eu, Yb) coordinated by alkyl,h alide, silylamido, and pyrazolato ligands can be synthesized by redoxt ransmetallation with the plumbocene derivativeC p* 2 Pb. [51,52] Herein,t he applicability of this elegant route in oxidation reactions with Ln II imidesw as probed. Accordingly, treatment of compounds 1-Ln and 2-Ln (Ln = Sm, Yb, Eu) with 0.5 equiv.Cp* 2 Pb per Ln II center in thf led to avisible reaction concomitant with the precipitation of elemental lead and ac olor change from purple to yellow (1-Sm, 2-Sm), yellow to purple (1-Yb), yellow to red (2-Yb), and yellow to orange (1-Eu, 2-Eu).…”

Nanoscale Organolanthanum Clusters: Nuclearity‐Directing Role of Cyclopentadienyl and Halogenido Ligands

“…Related mixed‐valent [Cp* 6 Yb 4 I 4 ] and [Cp* 5 Sm 5 I 9 ], Cp‐enriched congeners [Cp* 6 Yb 5 F 9 ] and [Cp* 6 Sm 5 Cl 9 ], as well as heterobimetallic [Cp 7 Dy 7 I 14 ](μ‐I)[Cp 2 V] form cluster motifs. Viable synthesis protocols for the half‐sandwich coordination clusters include salt metathesis, hydrogenolysis, thermolysis/desolvation, and Ln redox transformations . In the realm of Ziegler–Natta catalysts and respective model compounds, we have embarked on alkylaluminato/halogenido ligand exchange and donor‐promoted alkylaluminate cleavage of discrete half‐sandwich complexes [Cp*Ln(AlMe 4 ) 2 ] and gained access to {La 6 } and {Gd 8 } entities of the type [Cp* 6 La 6 Cl 8 (AlMe 4 ) 4 ] and [(Cp* 8 Gd 8 Me 4 (AlMe 4 ) 4 (CH 2 O t Bu) 8 ] .…”

“…Beside [Cp 12 Sm 12 Cl 24 ], the only other reported donor‐free CpLnX 2 derivatives comprise ring‐like [Cp* 4 Sc 4 I 8 ] and [Cp* 3 Dy 3 I 6 ] (Cp*=C 5 Me 5 ) . Related mixed‐valent [Cp* 6 Yb 4 I 4 ] and [Cp* 5 Sm 5 I 9 ], Cp‐enriched congeners [Cp* 6 Yb 5 F 9 ] and [Cp* 6 Sm 5 Cl 9 ], as well as heterobimetallic [Cp 7 Dy 7 I 14 ](μ‐I)[Cp 2 V] form cluster motifs. Viable synthesis protocols for the half‐sandwich coordination clusters include salt metathesis, hydrogenolysis, thermolysis/desolvation, and Ln redox transformations .…”