ISSN:
0044-2313
Keywords:
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Acyl- and Alkylidenearsines. IV. Molecular and Crystal Structure of 2,4-Di(tert. Butyl)-1,3-dimethyl-2,4-bis(trimethylsiloxy)-1,3-diarsetaneOn UV irradiation methyl-[2,2-dimethyl-l-(trimethylsiloxy)propylidene]arsine dimerizes to 2,4-di(tert. Butyl)-1,3-dimethyl-2,4-bis(trimethylsiloxy)-l,3-diarsetane 1. The compound crystallizes in the orthorhombic space group Pbca with: a = 12.829(4); b = 11.931(3); c = 33.23(1)Å; Z = 8. As it is found by a crystal structure determination (R = 5.6%) the molecule shows approximately C2-symmetry. The methyl groups at the arsenic atoms and the trimethylsiloxy groups are placed above, the tert.-butyl groups below the plane of the four membered ring which is slightly folded. The relatively long (2.05 Ä) arsenic-carbon bond-distances indicate a strained ring-system. Further characteristic average values are: As—CH3 1.96; C—0 1.40; Si—O 1.62 Å; ∢C—As—CH3 102.2° and 99.0° C—O—Si 156.3° in the ring: C—As—C 85.9°; As—C—As 92.5°.
Notes:
Unter UV-Bestrahlung dimerisiert Methyl-[2,2-dimethyl-l-(trimethylsiloxy)-propyliden]arsan zum 2,4-Di(tert. butyl)-l,3-dimethyl-2,4-bis(trimethylsiloxy)-l,3-diarsetan 1. Die Verbindung kristallisiert in der orthorhombischen Raumgruppe Pbca mit: a = 12,829(4); b = 11,931(3); c = 33,23(1) Å; Z = 8. Wie die Röntgenstrukturanalyse (R = 5,6%) zeigt, besitzt das Molekül angenähert C2-Symmetrie Die Methylgruppen an den Arsenatomen ordnen sich mit den Trimethylsiloxygruppen oberhalb, die tert.-Butylgruppen unterhalb der leicht gewinkelten Ringebene an. Die mit 2,05 Å langen Arsen-Kohlenstoff-Bindungen weisen auf ein gespanntes Ringsystem hin. Weitere charakteristische Mittelwerte sind: As—CH3 1,96; C—0 1,40; Si—O 1,62 Å; ∢C—As—CH3 102,2° u. 99,0°; C—O—Si 156,3° im Ring: C—As—C 85,9° As—C—As 92,5°.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19804700120
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