Acyclic, ring, and cage As,C compounds from trimethylsilyl ylides and AsCl3
Chemistry
; 6(19): 3531-9, 2000 Oct 02.
Article
em En
| MEDLINE
| ID: mdl-11072818
ABSTRACT
From the reaction of trimethylsilyl ylides with AsCl3 the dichloroarsanyl ylides 2b and 5b are obtained. As shown by X-ray structure determination, their AsCl2 groups deviate systematically from the symmetric orientation. This conformation enables an effective charge transfer from the ylide moiety to one of the As-Cl bonds, which as a consequence is up to 15 pm longer than the other. At the same time the length of the As-C bonds in 2b and 5b indicates a partial double bond. The effects observed here are of the same type as those observed for the corresponding dichlorophosphanyl ylides; they are, however, more pronounced. The 11 condensation of the bis(trimethylsilyl) ylide 3 and AsCl3 yields the oligomers (Ph3PCAsCl)2,3,4. The dimer 7b has a diarsetane structure. HCl adds readily to one of its As-C bonds without opening it. The trimer and the tetramer are ionic. The cation of the trimer forms a six-membered ring with a delocalized arsenium/phosphonium charge, the cation of the tetramer forms a barrelane cage with a phosphonio substituent, and the anion is AsCl4- in both cases (10, 13). An arsa-phosphocyanine cation as in 10 is also part of the diphosphonio isoarsindolide tetrachloroarsenate(III) 12. The structures of 7b.HCl, 10, and 13 reflect again an ylide to As-Cl charge transfer. The As-Cl bonds of 13 are by far the longest ones known for a chloroarsine (average 249 pm).
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01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Chemistry
Assunto da revista:
QUIMICA
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Alemanha
País de publicação:
ALEMANHA
/
ALEMANIA
/
DE
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DEUSTCHLAND
/
GERMANY