The Trishomocyclopropenyl Cation. I. Direct Observation

Abstract

The trishomocyclopropeny1 cation has been prepared for the first time and is shown to be a remarkably stable, highly charge-delocalized species. The large J 1 3 C -H value associated with the carbons formally carrying the positive charge, the high-field chemical shift of these carbons, and the absence of hydride shift, all are significant and are consistent with the formulation of 1 subject to the limit of the n.m.r. time scale.On a prepare le cation trishornocycloprop~nyle pour la premiere fois et dCmontrC que c'est une espece d'une stabilite remarquable et oh la charge est hautement delocalisee. Le fait que la valeur de J , 3 c -H soit grande pour les carbones portant la charge positive, de m&mk que le grand deplacernent chirnique vers les champs ClevCs de ces carbones, ainsi que ]'absence d e transfert d'hydrure sont tous significatifs et en accord avec la formulation de 1 dans les limites de I'CcheIle de temps de la r.m.n.[Traduit par le journal]Can. J. Chem., 52,855 (1974)

The Trishomocyclopropenyl Cation. II. An Ethano-bridged Derivative

“…As noted previously (1,4,6), chlorides appear to serve as the best precursors for the generation of cations in the present case. Thus, extraction of the chlorides 3 or 4 in CD2CI, with SbFSS02ClF at -120" provided yellow solutions which exhibited identical, clearly resolved 13C…”

“…6 1.44 peak, which readily leads to the assignment of this peak to H-8. The appearance of two approximate quartets at 6 0.86 and 2.90 suggested that these are a part of an AXM, system (confirmed by decoupling experiments) and the chemical shift values compare very well with those observed for Ha and He of 1 (1). Furthermore, these signals are virtually unaffected in the spectrum of 26 which showed no absorption at 6 1.17 and 3.64, and sharp and broad singlets at 6 1.98 and 2.10, respectively.…”

13C nuclear magnetic resonance study of five- and six-coordinated carbon in nonclassical organometallic compounds: Dimeric trialkyl-, tricyclopropyl-, and triarylaluminums and some nido and closo carboranes

“…In addition to extensive studies of tetravalent carbon compounds, in recent years nonclassical carbocations have been studied as stable species containing five-and sixcoordinated carbon atoms (18)(19)(20)(21)(22). 13C nuclear magnetic resonance (NMR) spectroscopy showed these carbon atoms to be highly shielded with respect to those of trivalent carbenium carbons.…”

Umlagerungen von Carbokationen

“…Diese Werte kommen auch quantitativ den Gasphasen-Daten (Tabelle 1) nahe und bestatigen den geringen Stabilitatsunterschied zwischeii sekundaren und tertiaren Norbornylkationen. [20]. Die verbruckte Struktur 36a kann man auch als ,,Trishomocyclopropenium-Ion" ansehen, da -das bedeutet das Prafix ,,homo" -jede C-C-Bindung des Cyclopropenium-Ions 37 durch C-CHZ-C ersetzt ist.…”