Cation charge repulsion

In the Polymer, Salt, Surfactant experiment, micelle bridging is the predominant mechanism. Shielding of the cationic charge repulsions occurs in... 

The p-phenylene-bis(diphenylcyclopropenium) dication, 39 (R = H), was found to have a />Kr+ value of -1.1, that is, the dication is less stable than the triphenylcyclopropenium cation (pkR+ = 2.8) by 1.7 pK units, again owing to charge-charge repulsion in this dication. 

In the ionic model, binding energies represent the nett effects of attraction between charges on the anions and central cation, repulsion between the anions and all electrons on the cation, and repulsion between the nuclei. The lattice energy, U0, of a binary ionic solid, such as periclase, may be expressed by the Bom equation, one form of which is... 

If NaCl is replaced by the butyl-3-methyl imidazolium (BMIM) chloride IL, a 30% decrease in retention factor associated with a remarkable peak shape improvement is observed. In this case, the IL cation adsorbs on the C18 stationary phase more than Cl", thereby preventing detrimental attractive silanophilic interaction of the cationic additive. Charge-charge repulsion occurs, the retention factor is lower, and the peak shape is better. The analyte cation is largely retained by hydrophobic fast interactions. When BMIM BF4 IL replaces NaCl, both the cation and anion of the IL adsorb on the C18 surface and all the interactions cited above take place simultaneously and contradict each other. Global retention depends on the extent to which one interaction is stronger than the other [124],... 

Using Paulings estimation for bond orders an overall bond order of 1.15 per Si-Si vector would give rise to a shortening of 4 pm to 232 pm. As there are charge repulsion and cation matrix effects to be considered, too, the observed distances seem to fit quite well with the n filling scheme. 

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