Electron photodetachment spectra of three alkoxide ions, 2,2-dimethyl-3-pentoxide, 3,3-dimethyl-2-butoxide, trifluoroethoxide, and two complex ions, 3,3-dimethyl-2-butanol/fluoride, 2,2-dimethyl-3-pentanol/fluoride, have been measured using an ion cyclotron spectrometer to generate, trap, and detect the ions. The electron affinities of trifluoroethoxide, 2,2-dimethyl-3-pentoxide, and 3,3-dimethyl-2-butoxide were measured as 58.9 ( 0.1, 47.8 ( 0.3, and 45.7 ( 0.1 kcal mol -1 , respectively. Using known proton affinities of the three alcohols allows us to determine the O-H bond dissociation energies. The threshold detachment energies for 2,2-dimethyl-3-pentanol/fluoride and 3,3-dimethyl-2-butanol/fluoride complex ions are 70.3 ( 0.5, and 70.1 ( 0.5 kcal mol -1 , respectively. The fluoride binding energies are thus on the order of 30 kcal mol -1 . We show that the observation or non-observation of photodetachment for alcohol/fluoride ions depends only on the alcohol acidity. In complex ions of the form ROHF -, if ROH is more acidic than HF the structure is RO -‚HF, and if ROH is less acidic than HF the structure is ROH‚F -. A flat potential energy surface model is consistent with the experimental results. The experimental results show no evidence for unusual structural change or stabilization when a hydrogen bond forms between two acids with similar acidities.

The electron affinity of the bis(dimethylphosphino)methyl radical was measured to be 35.3 ± 0.2 kcal/mol, using electron photodetachment spectroscopy in an ion cyclotron resonance spectrometer. Using equilibrium measurements, of bis(dimethylphosphino)methane and bis(trimethylsilyl)methane was determined to be 370 ± 3 and 373 ± 3 kcal/mol, respectively. From measured and known electron affinities and gas-phase acidities, we derive C−H bond dissociation energies:  bis(dimethylphosphino)methane, 92 ± 3 kcal/mol, and bis(trimethylsilyl)methane, 95 ± 3 kcal/mol. of trimethylphosphine was bracketed at 383−387 kcal/mol. The α-stabilization effect of silyl and phosphino substitution is large and comparable in size to stabilization by thio and chloro substitution. Possible mechanisms of stabilization are discussed.

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Gas-phase reactions of benzyl and methoxide anions with alkyl formate and other esters were compared using Fourier transform io cyclotron resonance spectroscopy. Although these anions have similar basicities, in many cases the reaction pathways differ.

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