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Low‐Temperature X‐ray Crystal‐Structure Analysis of the Thermally Unstable Lithiated 2‐Butenyl tert ‐Butyl Sulfide: A comparison with model ab initio MO calculations
Author(s) -
Seebach Dieter,
Maetzke Thomas,
Haynes Richard K.,
PaddonRow Michael N.,
Wong Stephen S.
Publication year - 1988
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19880710202
Subject(s) - chemistry , crystallography , reactivity (psychology) , crystal structure , bond length , allylic rearrangement , ab initio , ligand (biochemistry) , lithium (medication) , atom (system on chip) , tetramethylethylenediamine , moiety , double bond , stereochemistry , medicinal chemistry , polymer chemistry , organic chemistry , medicine , biochemistry , computer science , embedded system , endocrinology , catalysis , alternative medicine , receptor , pathology
Single crystals of the N,N,N ′, N ′‐tetramethylethylenediamine (TMEDA) complex 6 of the title compound have been isolated. Compound 6 decomposes in the crystalline state above −20°. From the bond lengths and angles obtained by X‐ray crystal‐structure analysis (data collected at −70°), compound 6 is best described as a ( E )‐1‐( tert ‐butylthio)‐1‐lithio‐2‐butene with the double bond acting as an additional ligand on lithium (unsymmetrical allylic group). The S‐atom is in a cisoid arrangement in a common plane with the four C‐atoms of the butenyl system. The t ‐Bu group and the Li‐atom are located above and below this plane. The structure is discussed with respect to the reactivity of 6 (α/γ reactivity). The gross structure is reproduced surprisingly well by an ab initio SCF MO calculation of the model lithiopropene‐1‐thiol 7 (HS instead of t ‐BuS, CH 2 instead of CHCH 3 , no solvation of Li). The prominent difference is the symmetry of the allyllic moiety in the calculated structure.