Röntgenstrukturuntersuchung von α‐(Trimethylsilyl)benzyllithium·Tetramethylendiamin [C₆H₅CH(SiMe₃)Li·TMEDA] und α‐(Phenylthio)‐benzyllithium·3 Tetrahydrofuran [C₆H₅CH(SPh)Li·(THF)₃] – zwei zentral‐chirale Benzyllithium‐Verbindungen

Abstract

Crystal Structure of α‐(Trimethylsilyl)benzyllithium·Tetramethylethylendiamin [C 6 H 5 CH(SiMe 3 )Li·TMEDA] und α‐(Phenylthio)‐benzyllithium·3 Tetrahydrofuran [C 6 H 5 CH(SPh)Li – (THF) 3 ] – Two Benzyllithium Compounds with Central Chirality The crystal structure analyses of [C 6 H 5 CH(SiMe 3 )Li·TMEDA] ( 6 ) and of [C 6 H 5 CH(SPh)Li·(THF) 3 ] ( 7 , in which the positions of the benzylic hydrogen atoms have been determined experimentally, reveal compounds with pyramidal benzylic carbon atoms. In 6 lithium is λ 2 ‐bound to C ipso and α of the substituted benzylic anion which leads, together with the TMEDA molecule, to a tetra‐coordinated lithium atom. In 7 only one Li – C bond is formed, namely that to C α . Additional coordination with three THF molecules results also in a tetracoordinated lithium atom, The extent of the pyramidalization in 6 and 7 is qualitatively in agreement with quantum‐mechanical ab initio calculations [G86, MP2/6‐311+ + G(d,p)].