TAS+(Z)-Me3CNSN- and TAS+(E)-Me3SiNSN-: does the anion-cation interaction influence the configuration?
TAS+ salts (TAS = (Me2N)3S) of the sulfur diimide anions Me3XNSN- (X = C (1a), Si (1b)) were prepared by Si-N bond cleavage from the corresponding sulfur diimides Me3XNSNSiMe3 and TAS-fluoride ((Me2N)3S+Me3SiF2-) and characterized by X-ray crystallography and multinuclear NMR spectroscopy. According to the experimentally determined bond lengths and theoretical calculations, the Me3XNSN- anions are best described as thiazylamides Me3X-N-S identical to N rather than sulfur diimides Me3X-N=S=N. In agreement with the calculated and experimentally determined structures of the isoelectronic thionylimides RNSO, 1a adopts the Z-configuration, which is electronically favored due to anomeric effects. The electronically disfavored E-configuration of 1b in the solid state can be explained by weak anion-cation interaction.
Borrmann
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T
Institute of Organic Chemistry, University of Bremen, Postfach 33 04 40, 28334 Bremen, Germany.
Zibarev
A V
AV
Lork
E
E
Knitter
G
G
Chen
S J
SJ
Watson
P G
PG
Cutin
E
E
Shakirov
M M
MM
Stohrer
W D
WD
Mews
R
R