Dissociative character

There are numerous approaches based on various assumptions explaining the dependence (2.1). They include supposition on dissociative character of chemisorption of O2 [24, 25, 53] developing through the following schematics ... 

The conclusion of the study [89] concerning non-dissociated character of hydrogen adsorption on semiconductors of ZnO type at low temperatures (lower than 70 C) was based on experimental facts indicating that hydrogen atoms which independently arrive at the surface of semi-... 

In the presence of an excess of reducing species, free radicals (R ), (R ) or/and (R ) are usually reduced very fast and owing to the probable dissociative character of the relevant electron transfer... 

Activation volumes for water exchange on [M(0H)(H20)5] (Table V) are all more positive than those measured on the corresponding hexa-aqua ions indicating a more dissociative character for the water-exchange reaction. The decrease in the positive charge at the metal center loosens the metal-water bonds and facilitates rupture of the M-0 bond. 

In summary it may be concluded that while the Grunwald-Winstein analysis m values may be useful in delineating the broad mechanistic features of octahedral complexes, attempts to probe the precise degree of associative and dissociative character in the reaction are not feasible. 

In equation (10), Y is the ionizing power of the solvent and N its nucleophilic power with m and / measuring the sensitivity of the substrate to these factors. By selecting model compounds, e.g. t-butyl chloride, where only Y should be important and methyl chloride, where both N and Y would be important, then it is possible to obtain values of Y and N for various solvent mixtures. An examination of the variation of the rate of reaction of a given substrate in these solvents according to equation (10) would then reveal the relative importance of the associative and dissociative character to the reactions. 

Almost in all cases (Table 3) photosubstitution reactive excited states are longer-lived spin-forbidden states involving an antibonding d-orbital of the central atom (usually dzi). The ability of complexes to undergo a photoejection of one axial ligand stems from the dissociative character of such a state. A special attention should be paid to complexes in metal-to-ligand charge-transfer (MLCT) reactive excited states (d, n ). On one side, the increase of positive... 

These molecules cause significant changes in the perceptual system, producing sensory illusions and inducing a distortion of reality, the sense of space and time, to the point of hallucination. Natural, synthetic or semisynthetic substances can cause hallucinogenic effects psilocin, psilocybin, mescaline, and LSD. Hallucinogenic effects are also created by phencyclidine and ketamine, but these molecules have a dissociative character. 

The quantum state of H2 molecule is characterized by the set of quantum numbers (N1 3A%,v ), where N1,3A refers to the electronic molecular state (N is the state principal quantum number in the united limit, A is the projection of total electron angular momentum, 1,3 (singlet, triplet) is the spin multiplicity of the state, a = g, u is the state symmetry, 7r is its parity) and v is the vibrational quantum number of N1,3A state. For simplicity, the indices (1,3), <7, 7r and A will, generally, be omitted in the reaction description. We note that many (NA) states of H2 have dissociative character. 

Hayami, J., Hihara, N., Kaji, A. Sn2 reactions in dipolar aprotic solvents. IX. An estimation of nucleophilicities and nucleofugicities of anionic nucleophiles studied in the reversible Finkelstein reactions of benzyl derivatives in acetonitrile - dissociative character of the reaction as studied by the nucleofugicity approach. Chem. Lett. 1979, 413-414. 

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