Latimer-diagram

FIG. 4 (a) Latimer diagram of the water soluble zinc tetra-Af-methyl-4-pyridium porphyrin (ZnTMPyP ). (Reprinted with permission from Ref. 47.) (b) Schematic representation of a photosynthetic process based on porphyrin sensitized water-organic interface. Dotted line corresponds to the back electron-transfer process. (Reprinted from Ref. 51 with permission from Elsevier Science.)... 

Figure L Modified Latimer diagram illustrating the relative reduction potentials of a metal complex (M) and its excited state (M ).

Figure 3. Modified Latimer diagram for the Re2Cl82 /Re2Cl9 system (E°/V...

Figure 5. Modified Latimer diagram for the Pt2(P2O5) s4 /Ph(Pz05)H8Cl24 ...

From the data provided we can construct the following Latimer diagram. 

The question marks in the original Latimer diagram have been replaced with letters in the diagram below to make the solution easier to follow ... 

In order for the disproportionation reaction to occur under standard conditions, the E° for the overall reaction must be greater than zero. To answer this question, we must refer to the Latimer diagrams provided in Figure 23-2 and the answer to practice example 23-IB. 

In order to add CIO2 to the Latimer diagram drawn above, we must calculate the voltages denoted by ( ) and ( ). The equation associated with the reduction potential ( ) is... 

The redox behavior of the [Tc04] ion is important in terms of understanding its chemistry. The Latimer diagram of important oxidation states and standard redox potentials is given in Scheme 4. The electrochemistry of technetium has been reviewed on several occasions. " ... 

In accordance with the general features of the chemistry of first-, second-, and third-row transition elements, the reduction potentials for the tetraoxometallates follow the sequences [MnOJ 3> [Tc04] > [ReOJ. The comparatively facile reduction of Tc , as evident from the Latimer diagram, limits the range of chemistry accessible for this oxidation state. 

The standard aqueous redox chemistry of vanadium and the other group 5 elements is summarized in the Latimer diagrams shown in Fig. 1 [2]. Under standard acidic aqueous conditions, the stability of the -1-5 oxidation state increases for the heavier group 5 elements at the expense of the +4 and -L3 states. 

Fig.1 Latimer diagram for the aqueous chemistry of the group 5 elements.

Latimer diagrams were invented by W. M. Latimer and consist of lines of text of the various oxidation states of an element arranged in descending order from left to right, with the appropriate standard reduction potentials (in volts) placed between each pair of states. The diagram for chromium in acid solution is written as ... 

For conciseness in the remainder of the chapter, the Latimer diagrams are presented with the relevant reduction potentials between the two oxidation states of the couple, as shown below, or in tabular form. 

The Latimer diagram for the states of chromium in standard alkaline solution [1 mol dm-3 OH (aq)] is ... 

Latimer diagrams are available for all the elements except for the unreactive lighter members of Group 18, and form an excellent and concise summary of the aqueous chemistry of such elements. They are used extensively in Chapters 6, 7 and 8. The diagrams used so far in the text consist of one line, but it is sometimes instructive to link oxidation states that are not adjacent to each other and to include the reduction potential appropriate to those states. One example is given in Figure 5.2 for some of the states of iron at pH = 0. 

Figure 5.2 A Latimer diagram for the +3, +2 and 0 oxidation states of iron reduction potentials...

Volt-equivalent diagrams convey the same amount of information as do Latimer diagrams about the relative stabilities of the oxidation states of an element and their oxidation/reduction properties, but do it in a graphical manner. Such diagrams are given in subsequent chapters for selected elements to illustrate further the differences in potentials between successive oxidation states. 

From the Latimer diagram for the element M. calculate the standard reduction potential for the M M reduction, and... 

The subject of this chapter is the periodicity of the aqueous chemistry of the elements of the s-block (Groups 1 and 2) and the p-block (Groups 11-18) of the Periodic Table. Modified Latimer diagrams summarize the chemistry of all the elements, and some volt-equivalent diagrams are given to represent the inter-relations between various oxidation states of the elements. Explanations of some trends in redox chemistry are discussed in detail. 

Nitrogen has some water-stable ions in which it has negative oxidation states. The Latimer diagram for these ions, the protonated forms of hydroxylamine, NH3OH +, and hydrazine, N2Hj, and the ammonium ion, NH4, is shown below ... 

W. M. Latimer, Oxidation Potentials. 2nd edn.. Prentice-Hall. New York, 1952. As its title implies, this book contains oxidation potentials (i.e. reduction potentials with their signs reversed, as was the convention at the time of its publication) for all the elements. This is a classic book, full of good chemistry, written by the inventor of Latimer diagrams and still available in libraries. 

The elements of the Group, including La and Lu, are powerful reducing agents, and their 4- 3/0 standard reduction potentials in I mol dm 3 acid solution are summarized by the Latimer diagrams shown in the margin. 

The redox chemistry of titanium, zirconium and hafnium in 1 mol dm 3 acid solution is summarized by the Latimer diagrams ... 

Volt-equivalent diagrams for the oxidation states of V are given in Figure 7.16 for pH values of 0 and 14. The reduction potentials on which the diagrams are based are given in the margin as a vertical Latimer diagram. 

A volt-equivalent diagram for the oxidation states of Ru is shown in Figure 7.22 for acid solution. The values of the potentials used to construct the diagram are given in the vertical Latimer diagram in the margin. 

The Group 9 elements, cobalt, rhodium and iridium, have redox chemistry which in aqueous acidic solution can be summarized by Latimer diagrams ... 

Of the Group 10 elements, nickel, palladium and platinum, only the +2 states of Ni and Pd are well characterized in aqueous acid solutions. Their + 2/0 standard reduction potentials in acid solution are given in the Latimer diagram ... 

Of the Group 12 elements, zinc, cadmium and mercury, only Hg has a water-stable -I-1 state, and all three elements have + 2 states that are water-stable. Their reduction potentials are summarized in the Latimer diagram ... 

Fig. 1. Estimated Latimer diagrams for the reduction of aqueous dioxygen calculated on the thermodynamic assumption of [02] = 1 M at pH = 0, 25°C. The overall four-electron process has the same potential (1.27 V) for both the chromium free and chromium mediated processes (14).

A Latimer diagram displays standard reduction potentials E°, connecting various oxidation states of an element.11 For example, in acid solution, the following standard reduction potentials are observed ... 

As an example to understand what the Latimer diagram means, the... 

We can derive reduction potentials for arrows that are not shown in the diagram by using AG°. For example, the reaction shown by the dashed line in the Latimer diagram is... 

For an advanced equilibrium problem based on the bromine Latimer diagram, see T. Michalowski, Calculation of pH and Potential E for Bromine Aqueous Solution, J. Chem. Ed. 1994, 71, 560. 

Latimer diagram One that shows the reduction potentials connecting a series of species containing an element in different oxidation states, law of mass action States that, for the chemical reaction aA + hB cC + dD, the condition at equilibrium is K JA C JA1, where... 

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