Allene, radical cations

Takemura and Shida54 prepared the allene radical ion by /-radiolysis of halocarbon solid solution of allene at low temperatures and showed that the radical cation has a lower D2 structure than the precursor with a skew angle of 30-40°. Kubonzo and coworkers55 56 produced by /-radiolysis in a low-temperature halocarbon matrix several derivatives of the allene radical cation, i.e. the radical cations of 1,2-butadiene, 3-methyl-1,2-butadiene,... 

Allene Radical Cations. The bimolecular reactivity of the radical reactions of allene and propyne has been a longstanding matter of interest. Myher and Harrison179 studied the ion/molecule reactions of ionized C3H4 with the respective neutral precursor in a medium-pressure chemical ionization source. CsH7+ ions were found to be amongst... 

Fig. 5. The A/B spectrum of the allene radical cation, (a) Experimental results from Ref. 33. (b) 10-mode model from Ref. 34. (c) 15-mode model from Ref. 35. The model spectra are the Fourier Ttansform of the autocorrelation function calculated using the MCTDH wavepacket propagation method. A damping function of t = 50fe has been used.

Fig. 6. The spectrum of the Jahn—Teller split A E state of the allene radical cation using different reduced dimensionality models, (a) A linear 2-mode model including the vibrational modes 02 and or with parameters adjusted to fit the spectrum, (b) A 2nd order 3-mode model including the vibrational modes 02, 03 and vr-...

Fig. 7. The time evolution of state population transfer in the A/B manifold of the allene radical cation after excitation to (a) the B B2) and (b) the X Ey) diabatic state.

The vibronic coupling model has been applied to a number of molecular systems, and used to evaluate the behavior of wavepackets over coupled surfaces [191]. Recent examples are the radical cation of allene [192,193], and benzene [194] (for further examples see references cited therein). It has also been used to explain the lack of structure in the S2 band of the pyrazine absoiption spectrum [109,173,174,195], and recently to study the photoisomerization of retina] [196],... 

Schmittel M., Woehrle C., Bohn I. Radical Cation Initiated Cycloaddition of Electron-Rich Allenes. Evidence for a Stepwise Mechanism. Acta Chem. Scand. 1997 57 151-157... 

Keywords radical cation, stepwise mechanism, electron-rich allenes... 

The structure of diphosphallenic radical cations, generated from the allene ArP=C=PAr by electrochemical oxidation, has been examined using EPR spectroscopy. Ab initio calculations including correlation effects at the MP2 and MCSCF levels have determined that two rotamers exist compatible with Jahn-Teller distortion of the allene.146 Anodically generated radical cations of alkyl phosphites [(RO P] and silylphosphites [(RO)2POSiMe3] reacted with alkenes by initial attack at the C=C bond followed by electron transfer, deprotonation, and elimination of an alkyl or trimethylsilyl cation to form identical alkyl phosphate adducts.147 The electron ionization-induced McLafferty rearrangement of n-hexylphosphine afford the a-distonic radical cation CTEPH, the distinct reactivity of which suggests there is no... 

Intermolecular reactions involving attack of /z-nucleophiles (even F") [262] at n radical cations include reactions at alkenes [263], allenes [264], aromatic systems... 

Y. Xie, W. D. Allen, Y. Yamaguchi, and H. F. Schaefer /. Chem. Phys., 104, 7615 (1996). Is the Oxywater Radical Cation Mote Stable Than Neutral Oxywater ... 

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