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Hetero‐ ansa ‐Bridged Main Group Metallocenes — a Structural and NMR Study
Author(s) -
Littger Ralf,
Metzler Nils,
Nöth Heinrich,
Wagner Matthias
Publication year - 1994
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19941271014
Subject(s) - chemistry , crystallography , monomer , nuclear magnetic resonance spectroscopy , metal , yield (engineering) , stereochemistry , group (periodic table) , main group element , potassium , crystal structure , transition metal , organic chemistry , materials science , metallurgy , catalysis , polymer
1,2‐Bis(dimethylamino)‐1,2‐di‐9‐fluorenyldiborane(4) (1) is doubly metallated with group 1 and 2 metals to yield metal 1,2‐bis(dimethylamino)‐1,2‐di‐9‐fluorenyldiborate(4) 2‐Li to 2‐Ba. The conformations of these compounds in solution are investigated by NMR spectroscopy, and the solid‐state structures of 2‐Li · 5 THF, 2‐K · 4 THF, 2‐K · 2 DME, and 2‐Ca · 2 THF are determined by X‐ray diffraction. All four structures can be described as main group metallocenes. The potassium derivatives form contact ion pairs, leading to polymeric chain‐like structures. In contrast, 2‐Li · 5 THF exhibits the rare combination of a contact ion pair with a solventseparated ion pair, giving the monomeric structure [Li(THF) 4 ][(fl 2 B 2 (NMe 2 ) 2 )Li · THF]. 2‐Ca · 2 THF, which is also monomeric, adapts a severely distorted geometry.