Are RR′C-PR″(BH3)2 'electron poor' phosphorus ylides? - An ab initio-NMR study

Alk Dransfeld, Anna Forro, T. Veszprémi, Michaela Flock, Minh Tho Nguyen

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3 Citations (Scopus)

Abstract

The parent RR′C-PR″(BH3)2, 3 (R, R′, R″ = H), has no minimum geometry with ylide structure. In contrast to 'normal' ylides, RR′C-PR″3, which are destabilised when the substituents (R, R′) have π donor character, the investigated RR′C-PR″(BH3)2 require at least one amino group to form a stable ylidic structure (e.g. 4NH with R = NH2, R′ = H, and R″ = H). Without π donor substituents the molecules lack a tautomerisation barrier for the hydroborylation (RR′C=PH(BH3)-BH2H′)→(RR′H′C- PH(BH3)=BH2). Compound 6, cyclo-1-(C-PH(BH3)2)-2,5-(NH)2-3, 4-(CH)2, is a model for the ylide recently obtained by Arduengo. Analysis of the electronic structure confirms his suggestion that a considerable delocalisation from the carbene moiety into the 'electron poor' PR″(BH3)2 group occurs. This electron delocalisation is reflected by the partial charge of the ylide group (-0.50 in 4HN, -0.51 in 4NN, and -0.85 in 6) which is negative (positive in 'normal' ylides). The term 'inverse ylides' could express this special bonding situation.

Original languageEnglish
Pages (from-to)2475-2482
Number of pages8
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number12
Publication statusPublished - Dec 2000

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Phosphorus
Nuclear magnetic resonance
Electrons
Electronic structure
Molecules
Geometry
carbene

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Are RR′C-PR″(BH3)2 'electron poor' phosphorus ylides? - An ab initio-NMR study. / Dransfeld, Alk; Forro, Anna; Veszprémi, T.; Flock, Michaela; Nguyen, Minh Tho.

In: Journal of the Chemical Society, Perkin Transactions 2, No. 12, 12.2000, p. 2475-2482.

Research output: Contribution to journalArticle

Dransfeld, Alk ; Forro, Anna ; Veszprémi, T. ; Flock, Michaela ; Nguyen, Minh Tho. / Are RR′C-PR″(BH3)2 'electron poor' phosphorus ylides? - An ab initio-NMR study. In: Journal of the Chemical Society, Perkin Transactions 2. 2000 ; No. 12. pp. 2475-2482.
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