Formal charge hydrate

In reverse to solubilization, soluble polysaccharides are made less soluble by removing branches or substituents to produce a more uniformly linear polysaccharide with improved possibility of intermolecular fit, by removing formal charges, by lessening the number of strong hydration sites, or by completely overcoming hydration effects by introducing hydrophobic substituents. 

Figure 37 shows the formal charge of 1 as a fimction of distance from a Ptg cluster, obtained by Mulliken population analysis of ab initio calculations of Pt9l clusters [115, 239]. The effect of solvation on the partial charge of the hydrated iodide ion near the Pt(lOO) surface was investigated [234] by a combination of quantum chemical calculations, the Anderson-Newns model of chemisorption and MD calculations of the free energy of iodide adsorption [190]. On the basis of the approximations discussed in Ref. 234, the charge on the bare ion can also be calculated from the relation... 

Fig. 7.1 A separation of metal ions and mettaloid ions, As(lll) and Sb(lll), into three categories class A, borderline, and class B ions. The class B index X r is plotted for each ion against the class A index Z /r. In these expression is the metal-ion electronegativity, r its ionic radius, and Z its formal charge. Oxidation states given by Roman numerals imply that simple, hydrated cations do not exist even in acidic solutions. (Reprinted from Nieboer and Richardson (1980), Copyright 2002, with permission from Elsevier Science).

The hydrated proton, so far in this text, has been written as H+(aq), but a bare proton might be expected to interact very strongly with a water molecule to give the ion, H30+, that would also be hydrated and written as H30+(aq). The interaction takes the form of an extra covalent bond between a hydrogen atom and the formally positively charged O1 ion, itself electronically identical with the nitrogen atom. The H30+ ion is isoelectronic with the NH3 molecule. The ion H30+ is called variously hydronium, hydroxonium or nximium. 

---