Equivalent neutral class

The equivalent neutral class formula ([ML/X -ZJ) permits comparison of these iron complexes, and provides ready access to other information about these complexes. For example,... 

Covalent Bond Classification Method 523 TABLE 13.9 Information Available from the Equivalent Neutral Class Formula... 

Use the Covalent Bond Classification Method to classify these complexes with a [ML/X ZJ formula. With charged species, reduce the formula to its equivalent neutral class. 

Use the Covalent Bond Classification Method to classify these hypothesized complexes with a [ML/X ] formula. With charged species, reduce the formula to its equivalent neutral class. On the basis on the MLX plot for iron in Section 13.7, speculate on the likelihood that the following iron complexes have been prepared. 

This reaction results in formal oxidation of the metal (from Mo(0) to Mo(ll)) and the coordination number increases by 1 (by the CBC method an [ML5X] complex (equivalent neutral class is ML5) changes to an ML5X2 complex) as the iodide is expelled. 

Each added negative charge is considered to convert an X ligand to an L, giving the equivalent neutral class formula ML2X2. 

Mo(PR3)3(0)Cl2, respectively." The [X2] bar notation indicates that the two X-functions belong to a single atom (a so-called polyfunctional ligating atom) and the distinction is only of significance with respect to reducing an anion to its equivalent neutral class (see Section 1.01.4.2). 

Figure 27 [ML/X ZJ classifications of some simple tungsten compounds. Note that the initially derived [ML4X5l classification of [Cp2WH3]+ is transformed to the equivalent neutral class of MLsXg upon applying the rule...

Figure 28 Orbital explanation for the rules used to transform [ML xZz] " to its equivalent neutral class. Note that the transformation Xj - (L X for a polyfunctional atom means that due consideration must be given to evaluate whether the L function remains involved in the bonding or whether it becomes a lone pair localized on the ligand.

The valence number (VN) of the metal center, i.e. the number of electrons that the metal uses in bonding, is VN =x+Zz. In most organotransition metal complexes, the number of Z ligands in the equivalent neutral class is zero. As such, the valence number is typically equal to, i.e. the number of one-electron donor X-ligands. The value of the d" configuration is given hy n = m — x — Zz = m — VN. 

The reason for % being 0 is a consequence of the fact that organotransition metal molecules that contain a Z function ligand invariably possess an L function ligand, with the result that the combined LZ function transforms to the X2 description. Molecules that contain a Z function in the classification are, nevertheless known for example, [NH4] is classified as [NX3Z] upon reducing the [NX4] classification to the equivalent neutral class using the rule that X = Z. 

Transportation and Disposal. Only highly alkaline forms of soluble sihcates are regulated by the U.S. Department of Transportation (DOT) as hazardous materials for transportation. When discarded, these ate classified as hazardous waste under the Resource Conservation and Recovery Act (RCRA). Typical members of this class are sodium sihcate solutions having sihca-to-alkah ratios of less than 1.6 and sodium sihcate powders with ratios of less than 1.0. In the recommended treatment and disposal method, the soluble sihcates are neutralized with aqueous acid (6 Af or equivalent), and the resulting sihca gel is disposed of according to local, state, and federal regulations. The neutral hquid, a salt solution, can be flushed iato sewer systems (86). 

An intriguing class of persistent radicals are those formed by the one-electron oxidation of the hexagonal prismatic clusters Li2[E(N Bu)3] 2 (3.21, E = S, Se). The air oxidation of 3.21 produces deep blue (E = S) or green (E = Se) solutions in toluene. The EPR spectra of these solutions consist of a septet (1 3 6 7 6 3 1) of decets (Eig. 3.5). This pattern results from interaction of the unpaired electron with three equivalent 7=1 nuclei, i.e., and three equivalent I = 3/2 nuclei, i.e., Ei. It has been proposed that the one-electron oxidation of 3.21 is accompanied by the removal of an Ei" cation from the cluster to give the neutral radical 3.22 in which the dianion [S(N Bu)3] and the radical monoanion [S(N Bu)3] are bridged by three Ei" cations. 

Solubility in both 5% sodium hydroxide and sodium bicarbonate is usually sufficient to characterize this class of compounds. Addition of mineral acid should regenerate the carboxylic acid. The neutralization equivalent can be obtained by titrating a known quantity of the acid (ca. 50 mg) dissolved in water-ethanol with 0.1 N sodium hydroxide to a phenolphthalein end point. 

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