Clusters hydrogen migration

A characteristic cluster of ions resulting from an a cleavage and hydrogen migration in monoalkylben-zenes appears at m/z 77 (C6H5+), 78 (C6H6+), and 79... 

The dominant isomerization pathway for the trimeric allenyl clusters [M3H(CO)9(/Li3-i7, V> 7 I C =C=CHR)] is via a thermal 1,2-hydrogen migration to afford the 1,3-dimetalloallyl clusters [M3H(CO)9(/H3-i7, t7, t7 -RCCHCR)] (53c). Reaction of alkynes and dienes with metal carbonyls M3(C0)2 (M = Ru, Os) often occurs with C-H activation adjacent to the unsaturated carbon-carbon bond (54) however, the final products isolated are often of the 1,3-dimetalloallyl type, the intermediate allenyl complex formed being thermodynamically unstable under the reaction conditions necessary to initiate C-H activation. 

Fig. 10 Characterization of the excited-state quenching mechanism in TME for three different environments. The pressurized argon cluster (orange, Ar) leads to enhancement of population transfer through hydrogen migration (H Mig) intersections, compared to isolated TME (red. Gas). Fixing the argon atoms in the cluster (blue, Ar-Fixed) leads to a dramatic enhancement of population transfer through C-C stretched intersections, which require little motion of the methyl groups...

In order to develop more informative and direct method of studying the spillover effect of active particles, the authors of [37] suggested to use the sensor method of detecting migrating particles based on separation of sensor and emitter (donor) of active particles. The latter consists of small metal globules, or clusters (with a diameter of about 20-30 A) of Pt, Pd, Ni, etc. (activator) deposited on quartz or sapphire (AI2O3) plate in the form of a strip less than 1 cm wide. The sensor for detection of hydrogen atoms consisted of a zinc oxide strip (with a width of about 0.1 cm and thickness wlOO nm) deposited on the same plate at a distance of 0.03 or 0.6 cm (two versions) from the inner boundaries of activator strips [38]. 

The situation for hydrated Nafion in the acid form, or as containing aqueous acids or strong bases, is more complex because protons and defect protons (i.e., OH ions), migrate according to a somewhat different mechanism. Proton transfer in either case occurs throughout and between clusters of hydrogen bonded water molecules to a degree that depends on the relative water content. 

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