Premium
Crystal Structures and 29 Si NMR Calculations of Amino‐Functionalized Silyllithium Compounds
Author(s) -
Strohmann Carsten,
Ulbrich Oliver,
Auer Dominik
Publication year - 2001
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200104)2001:4<1013::aid-ejic1013>3.0.co;2-5
Subject(s) - tetrahydrofuran , chemistry , lithium (medication) , crystallography , silicon , bond length , chemical shift , nuclear magnetic resonance spectroscopy , crystal structure , stereochemistry , organic chemistry , medicine , solvent , endocrinology
Abstract X‐ray structural analysis of the amino‐functionalized silyllithium compounds tris(tetrahydrofuran)[bis(diethylamino)phenylsilyl]lithium ( 4· 3THF) and tris(tetrahydrofuran)[(diethylamino)bisphenylsilyl]lithium ( 7· 3THF) are presented. Both compounds are monomeric in the solid state as well as in solution. Despite the formal negative charge at the silicon atom, the nitrogen centres are flattened. No Li−N interactions were observed, in contrast to the homologous (lithiomethyl)amines. RI‐DFT calculations give an explanation for the variation of experimental Si−Li bond lengths of 2.627(4) Å ( 4· 3THF), 2.682(8) Å ( 7· 3THF) and 2.732(7) Å {tris(tetrahydrofuran)[bis(diphenylamino)phenylsilyl]lithium} ( 1· 3THF). N−Si orbital interactions, influenced by the type of substituents located at the nitrogen centre, affect these structural parameters as well as the 29 Si NMR chemical shifts. The apparently unusual experimental values of the 29 Si NMR resonance signals at δ = 20.3 (for 7· 3THF) and δ = 28.4 (for 4· 3THF) can be explained by DFT‐IGLO calculations and are a consequence of the combination of electronegative and electropositive substituents at the silicon centre.