Higher valent atom

For a monograph on abstractions of divalent and higher valent atoms, see Ingold, K.U. Roberts, B.P. Free-Radical Substitution Reactions, Wiley NY, 1971. 

Finally, from x = 0.98 until x = 1.0, a solution of copper in the zinc matrix is observed. The regions of homogeneous solutions are examples of Hume-Rothery s third rule. The higher valent atom (zinc) is more soluble in the lower valent solvent (copper) then vice versa. 

We have covered several oxidants that use a multi-valent atom (Cr, Cl, S, or I) as their active species, going from a higher oxidation state before the oxidation to a lower oxidation state after oxidizing the alcohol. Draw the structure of the following atoms, before and after the oxidation of an alcohol to a ketone or aldehyde. How many bonds to oxygen does each atom have before and after the oxidation ... 

Thus, certain structural features, in particular incorporation of the central atom into a five-membered ring, chelate, macrocyclic and cryptate effects may stabilize the geometry of penta- and hexa-coordinate silicon species. Much of the insight as to which structural features might be expected to stabilize this species comes from studies of species involving higher valent states of other nonmetallic elements of the third row of the periodic table os-so )... 

In this case the metal atom is a part of the polymer chain (structure G). To realize such an arrangement with the mentioned ligands four-or higher valent metal atoms like Si, Se, Sn and other may be taken. 

So pronounced is the chelating tendency of the diketonate anion that even alkali metal complexes may be isolated, as illustrated by RbiKCFjCOCHCOCFjljNa], in which sodium is surrounded by a trigonal prismatic array of donor oxygen atoms. For complexes derived from dibenzoylmetbane, stabilities in dioxane-water are in the order Li > Na > K > Cs. For divalent metal ions formation constants increase in the order Ba > Sr > Ca > Mg > Cd > Mn > Pb > Zn > Co, Ni, Fe > Cu, and for higher valent metal ions the first formation constants for chelates are in the order Fe + > Ga " " > Th" > In " " > Sc " " > Y " " > Sm " > Nd " > More recently, such stu-... 

If it were possible to use in Table 2 (p. 270) only ideal 6, 5, 4, and 3 valent mono-atomic cations (La and Ce being the only ideal cases of 3 valent cations, A1 and Th already behaving as large complex ions, see p. 291, and the still higher valent cations not existing at all) then the sulphate colloids would behave totally otherwise than the phosphate and carboxyl colloids (horizontal rows consisting presumably only in minus signs). 

Let s now consider whether the representation chosen—the traditional one with multiple bonds versus the newer one—affects the valence of the central atom. Let us do so with a couple of examples involving higher-valent sulfur, say, SOCI2 and SO2CI2. If we consider the traditional structural formulas with double bonds, the S is clearly tetra- and hexa-valent in the two molecules, respectively. Simply count the electrons, denoted by blue dots, that the sulfur has used to form bonds. 

Many higher-valent p-block oxides, broadly defined, effect oxygen atom transfers to lower-valent p-block compounds. DFT calculations in the authors laboratory suggest that the mechanisms are best viewed as direct SN2-like displacements and do not involve oxo-bridged intermediates. 

An awkward aspect of each of the above steps is that the nucleophile is a chlorine with a positive formal charge. Once again, when dealing with higher-valent compounds, this need not be particularly upsetting. Formal charges are simply an electron-bookkeeping device and do not provide a realistic indication of the electrostatic character of atoms. 

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