The hydration state of HO−^-(aq)

The HO$^-$(aq) ion participates in myriad aqueous phase chemical processes of biological and chemical interest. A molecularly valid description of its hydration state, currently poorly understood, is a natural prerequisite to modeling chemical transformations involving HO$^-$(aq). Here it is shown that the statistical mechanical quasi-chemical theory of solutions predicts that $\mathrm{HO\cdot[H_2O]_3{}^-}$ is the dominant inner shell coordination structure for HO$^-$(aq) under standard conditions. Experimental observations and other theoretical calculations are adduced to support this conclusion. Hydration free energies of neutral combinations of simple cations with HO$^-$(aq) are evaluated and agree well with experimental values.Comment: 10 pages, 1 figur

Hydride abstraction from 1,3,5-cycloheptatriene by gaseous carbenium ions, as studied by Fourier transform ion cyclotron resonance kinetics and deuterium labeling

Mormann M, Kuck D. Hydride abstraction from 1,3,5-cycloheptatriene by gaseous carbenium ions, as studied by Fourier transform ion cyclotron resonance kinetics and deuterium labeling. JOURNAL OF PHYSICAL ORGANIC CHEMISTRY. 2003;16(10):746-752.The gas-phase interaction of protonated acetone and tert-butyl cations with 1,3,5-cycloheptatriene was studied by Fourier transform ion cyclotron resonance (Fr-ICR) mass spectrometry. In addition to proton transfer giving C7H9+ ions, hydride abstraction from cycloheptatriene giving C7H7+ ions was observed. Deuterium labeling 9 experiments combined with the determination of the reaction kinetics excluded the formation of C-7-H-7(+) ions by consecutive proton transfer and H-2 expulsion under these conditions. The kinetic isotope effect measured for the hydride transfer channel was found to be in the range 1.65 +/- 0.1, very close to that known to operate during hydride transfer from simple alkylbenzenes to t-C4H9+ ions. Copyright (C) 2003 John Wiley Sons, Ltd