ISSN:
1434-1948
Keywords:
Double Bonds
;
NMR Spectroscopy
;
Silicon
;
Tin
;
X-ray structure analyses
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The dark blue, air- and moisture-sensitive, thermolabile tristannaallene R*2Sn=Sn=SnR*2 (5) (R* = SitBu3) is prepared by reaction of Sn(OtBu)2 or Sn[N(SiMe3)2]2 with R*Na in pentane/benzene at -25°C. The dark red-brown, air-sensitive, moisture-insensitive, and thermostable cyclotri-stannene R*4Sn3 (6) with a -R*Sn=SnR*- moiety as part of a Sn3 ring is obtained from the reaction of Sn(OtBu)2 or Sn[N(SiMe3)2]2 with R*Na in pentane at 25°C or from the isomerization of 5 at room temperature (τ1/2 = 9.8 h). According to the result of X-ray structural analyses the Sn3 framework of chiral 5 is bent (156°) and the terminal Sn atoms have pyramidal surroundings. The SnSn double bonds in 5 (2.68 Å) are shorter than those found for the hitherto structurally investigated distannenes (2.77-2.91 Å). Even shorter is the double bond in 6 (2.59 Å). The unsaturated Sn atoms here have nearly planar surroundings in perfect analogy to the carbon atoms in CC double bonds. The SnSn double bond in 6 can therefore be considered as the first “true” Sn=Sn bond. The structures of 5 and 6 can be deduced also from 119Sn- and 29Si-NMR studies in solution.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
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