Oxidation state minimum

The rules above gave maximum and minimum oxidation numbers, but those might not be the only oxidation numbers or even the most important oxidation numbers for an element. Elements of the last six groups of the periodic table for example may have several oxidation numbers in their compounds, most of which vary from each other in steps of 2. For example, the major oxidation states of chlorine in its compounds are -1, +1, +3, +5, and +7. The transition metals have oxidation numbers that may vary from each other in steps of 1. The inner transition elements mostly form oxidation states of + 3, but the first part of the actinoid series acts more like transition elements and the elements have... 

The P clusters of nitrogenase. The enzyme nitrogenase consists of two proteins the Fe protein (m.w. 55,000), which contains a single 4Fe-4S center, and the more complex MoFe protein (m.w. 220,000) (48,49). The minimum functional unit of the latter appears to be the half molecule, an asymmetric dimer containing 1 Mo, 14-16 Fe, and 16-18 sulfides. Application of a vast array of spectroscopic methods to the MoFe protein in a variety of oxidation states has led to the conclusion that it contains two types of metal-sulfur cluster in a 2 1 ratio unusual Fe S units termed P clusters, and the protein-bound form of the FeMo-cofactor (50). 

The emf values for oxidation of the oxygen in water are given in Eqs. 10.119 to 10.121. These determine the minimum reduction emf necessary fora species to effect oxidation of the oxygen I M acid, ° > +1.229 V neutral solution, E > +0.815 V I M base, ° > +0.40J V. There are several oxidation states of manganese that are reduced by water, but the protonated manganate ion is typical ... 

Although the number of valence electrons present on an atom places definite restrictions on the maximum formal oxidation state possible for a given transition element in chemical combination, in condensed phases, at least, there seem to be no a priori restrictions on minimum formal oxidation states. In future studies we hope to arrive at some definitive conclusions on how much negative charge can be added to a metal center before reduction and/or loss of coordinated ligands occur. Answers to these questions will ultimately define the boundaries of superreduced transition metal chemistry and also provide insight on the relative susceptibility of coordinated ligands to reduction, an area that has attracted substantial interest (98,117-119). 

The valence electron configuration of the group 5A elements is ns2 np3. They exhibit a maximum oxidation state of +5 in compounds such as HNO3 and PF5/ in which they share all five valence electrons with a more electronegative element. They show a minimum oxidation state of —3 in compounds such as NH3 and PH3/ where they share three valence electrons with a less electronegative element. The —3 state also occurs in ionic compounds such as Li3N and Mg3N2, which contain the N3- anion. 

For hexa-coordination, the metal atoms are usually found in their highest oxidation state corresponding to a minimum radius for the element. The experimental results support theoretical analysis [44], in that the optimum arrangement of six monodentate ligands around a metal atom is octahedral. In the case of non-identical ligands, the metal-ligand... 

The maximum oxidation number of sulfur is +6, equal to its group number. Sulfur also has the oxidation state 0 when it is not combined and a minimum oxidation state of 6 - 8 = -2. (Sulfur can also have oxidation states +4 and + 2, not covered by the rules given so far.)... 

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