Reactions of the transition metal halide complexes [MXL2(Cp)] (M = Fe, X = I, L2 = dppe; M = Ru, X = Cl, L = PPh3; M = Os, X = Br, L = PPh3; Cp = η-C5H5) with the alkynol HCCCH(OH)(Fc) (1) (Fc = ferrocenyl) in the presence of TlBF4 gave the monosubstituted allenylidene complexes [M(CCCHFc)L2(Cp)][BF4] (2a: M = Ru, L = PPh3; 3: M = Fe, L2 = dppe; 4: M = Os, L = PPh3). Similarly, the reaction of 1 with [RuCl(PPh3)2(Cp)] and NH4PF6 in methanol gave [Ru(CCCHFc)(PPh3)2(Cp)][PF6] (2b). These highly colored compounds were characterized by spectroscopic and electrochemical techniques and in the case of 2b by a single-crystal X-ray structure determination. Cyclic voltammetry in MeCN in the presence of [nBu4N][ClO4] at 100 mV·s−1 shows a reversible ferrocenyl-based one-electron oxidation, in addition to irreversible oxidation and reduction processes. The NMR spectra of 2b show complex behavior at low temperature, attributed to temperature-dependent chemical shifts and correlated motions of the allenylidene ligand and the ferrocenyl substituent.
Near-thermal lSF atoms, produced by the 19F(n,2n)18F nuclear reaction and moderated in kinetic energy by collisions with excess SFs, have been reacted with the fluorinated ethylenes. The radicals formed by '8F addition are predominantly collisionally stabilized at 5 atm of pressure and are identified after abstraction of H from HI as the corresponding fluoroalkane-l*F. In intermolecular competition, the 18F atoms react preferentially with less fluorinated positions. Intramolecularly, I8F addition is also preferred at the less fluorinated end of the molecule. The competitive reaction ratios per molecule are generally independent of olefin/HI ratios, as well as of the ratios of two competing olefinic substrate molecules. The decomposition by CF, loss of CHFI8FCF2* radicals from near-thermal addition of 18F to CHF==CF2 proceeds with a pressure for half stabilization of 45 i 5 Torr in CHF=CF2.he energetic 18F atoms formed by nuclear reactions
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