Tetrameres und dodecamerestert-Butylethinyllithium; ein neuartiges Aggregationsprinzip bei Organolithiumverbindungen

Abstract

Chem. 90 (1978) 144: Angew. Chem. Inr. Ed. Engl. 17 (1978) 124. Dort ist Herstellung und Struktur eines tetrameren Komplexeb von 6 mit Tricyclohexylphosphan als Ligand beschrieben.

Isolation and Structure Analysis of Neohexyllithium Generated by Ether Cleavage: Primary and Secondary Coordination in Alkyllithium Aggregates

“…The distance to the coordinating THF molecule is 1.946(5) Å (Li1−O1). Thus, the structural parameters observed for 3 are similar to those determined in related structures (for comparison, average distances for Li−Li, Li−C α , and Li−O solvent in [MeLi·THF] 4 are 2.51, 2.24, 1.96 Å, in [ n BuLi·THF] 4 are 2.54, 2.24, and 1.97 Å, and in [ t BuC⋮CLi·THF] 4 are 2.69, 2.19, 1.96 Å). However, the arrangement of the alkyl groups in 3 differs significantly from the conformation observed in solvent-free aggregates.…”

Synthesis and Characterization of Alkynyl Complexes of Groups 1 and 2

“…[7,8] The compounds [tBuC CLi·thf] 4 (3) and [(tBuC CLi) 12 A C H T U N G T R E N N U N G (thf) 4 ] (4) were obtained from THF-containing solutions of tBuC CLi at À78 8C and at room temperature, respectively, and were characterized by X-ray single crystal structural analysis. [9] However, arising from the sensitivity of the compounds and loss of THF of the crystals, the data could only be refined up to R-factors of 16-17 % for 3 and 4. There is a renaissance in the field of magnesium alkynyl compounds in recent years.…”

“…Herein, we report the synthesis and characterization of 1:1 adducts of tBuC CLi and (tBuC C) 2 Mg with NHC, giving [tBuC CLi·NHC] 4 (8) and [(tBuC C) 2 Mg·NHC] 2 (9), respectively, and a well-defined molecular mono stronti- (10) prepared from the reaction of PhC CH with the strontium amide 7. The strontium alkynyl complex 10 is compared with its lighter (11).…”

“…Dimers as well as tetramers of RC≡CLi were detected in THF solutions 7. 8 The compounds [ t BuC≡CLi⋅thf] 4 ( 3 ) and [( t BuC≡CLi) 12 (thf) 4 ] ( 4 ) were obtained from THF‐containing solutions of t BuC≡CLi at −78 °C and at room temperature, respectively, and were characterized by X‐ray single crystal structural analysis 9. However, arising from the sensitivity of the compounds and loss of THF of the crystals, the data could only be refined up to R‐ factors of 16–17 % for 3 and 4 .…”

[{(MeLi)4(dem)1.5}∞] and [(thf)3Li3Me{(NtBu)3S}]—How to Reduce Aggregation of Parent Methyllithium

“…The dominant aggregation polyhedron in parent organolithium solid‐state structures4 is the tetrahedron in [(MeLi) 4 ],5 [(EtLi) 4 ],6 and [( t BuLi) 4 ]7 and the octahedron in [( n BuLi) 6 ],7 [( i PrLi) 6 ],8 [(CyLi) 6 ]9 (Cy=cylohexyl), [{(Me 2 C) 2 CHCH 2 Li} 6 ],10 and [(Me 3 SiCH 2 Li) 6 ]11 made up of four or six lithium atoms, respectively, with the α ‐carbon capping an Li 3 face of the deltahedron. As the [{MeLi} 4 ] tetramer persists in the known solvated MeLi structures, the tetrahedron seems to be the favorite aggregate of solvated lithium organics like [{MeLi(thf)} 4 ],12 [{ n BuLi(thf)} 4 ],13 [{ t BuCH 2 CH 2 Li(thf)} 4 ],14 and [{ t BuC≡CLi(thf)} 4 ] 15. This structural motif is maintained when the donating group is intramolecular provided in a side arm donation like in [{MeO(CH 2 ) 2 (Me)CHLi} 4 ],16 [{MeO(CH 2 ) 2 CH 2 Li} 4 ],17 and [(H 10 C 5 NCH 2 Li) 4 (thf) 2 ] 18.…”