Hydronium cation-water complex

Geminate recombinations and spur reactions have been widely studied in water, both experimentally and theoretically [13-16], and also in a few alcohols [17,18]. Typically, recombinations occur on a timescale of tens to hundreds of picoseconds. In general, the primary cation undergoes a fast proton transfer reaction with a solvent molecule to produce the stable solvated proton and the free radical. Consequently, the recombination processes are complex and depend on the solvent. The central problem in the theory of geminate ion recombination is to describe the relative motion and reaction between the two particles with opposite charges initially separated by a distance rg. In water, the primary products of solvent radiolysis are the hydrated electron e ", the hydroxyl radical OH and the hydronium cation H3O+ ... 

Newton and Fhrenson (34) obtained a mininum enerpy confipuration for the Hydronium ion which was planar, contrary to expectations. A more expensive computation by Kollman and Pender (351 was repui ed to obtain pyramidal distortion(36). Die substitution of Lithium cation for proton in the hydronium ion is not an isoelectronic replacement, and the arpument by analopy need not hold. Tlie suppestion is nevertheless painfully clear that the ion should not be planar. Since hiph accuracy Quantum Mechanical computations are quite expensive, one can perhaps understand v hy "frozen peometry water molecules have been used in these Lithium-water complex ion computations, and therefore why planar, triponal structures have always been found to be most favored. 

Soil pH is perhaps the most critical and common soil measurement where a definite amount of water is added before a measurement is made. Soil pH is a particularly complicated measurement because the proton can and does exist as a hydronium ion in the soil solution, as an exchangeable ion on the cation exchange sites, and bonded to various soil constituents. Because of these complexities, a soil sample is usually brought to a standard moisture content before a pH measurement is made. By bringing different soils to a common moisture content, they can be compared and analytical results from different laboratories will be comparable. Although there is a number of ways to measure soil pH, typically it is carried out using a pH meter and a pH electrode. 

Fedin and coworkers [102,103] have isolated a number of distinct species within CB[n] nanoreactors. For example, they identified a previously unrecognized hydronium di-cation in a solid-state complex with CB[6] [102]. Instead of the commonly recognized H7 O3 monocation (essentially a proton coordinated by three water molecules), they observed a cyclic H14 OJ species, stabilized and templated by a set of five hydrogen bonds to the CB[6] portal carbonyls, forming an exclusion complex. In another report, they showed that the trans form of the metal complex [Co(en)2Cl2r (en = ethylenediamine) was selectively encapsulated in CB[8] from a mixture of cis and trans complexes [103]. Furthermore, the trans complex was thermally stabilized in the CB[8] nanoreactor. This shows the potential utility of CB[n] nanoreactors to select specific reactant isomers for subsequent selective reactions. 

Single crystals of the bromo complex were grown in concentrated HBr. The cesium TcjBrg " salt crystallizes in the trigonal space group P 2 [44]. The crystals contain Tc Brg " anions, cesium cations, hydronium ions, and water molecules. The stoichiometry - )]Tc2Brg-4.6H20,... 

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