Oxidation states assignment

The oxidation state of Au in both Au-oxo complexes 3 and 4 was thoroughly investigated by several chemical and physicochemical methods 44). First, bulk electrolysis (coulometry at controlled potential) confirms the Au(III) oxidation state assignment in both 3... 

Tab. 7 Redox potentials and oxidation state assignments of photosystem II components...

The extensive electron delocalization in bis(dithiolene) complexes makes it possible for them to exist in a range of charge levels. It also makes oxidation state assignment of the metal and ligands potentially ambiguous. Mononuclear bis(dithiolene) complexes can undergo one, two, or even three reversible... 

NITROSYL COMPLEXES AND OTHERS WHERE AN AMBIGUITY IN OXIDATION STATE ASSIGNMENT MAY EXIST... 

The iridium(II) complex [Ir(Br)3(NO)(PPh3)2] has been reported by Malatesta and coworkers.7 A + II oxidation state assignment depends on the formalism used regarding the nitrosyl ligand. The complex is considered iridium(II) if the NO ligand is assigned as (NO)+. 

CW 35 GHz ENDOR, of the individual Fe sites in the CO-inhibited forms,much as had been done earlier for resting state FeMo-cofactor. " Hyperfine coupling constants were determined for four Fe sites in the lo-CO and three in the high-CO forms. The signs and magnitudes of the Ajj, Fe values, in comparison with those of other FeS proteins and with extensive computational studies, allowed a proposal as to the formal oxidation state assignments of the metal ions in the FeMo-cofactor as [Fe7S9Mo]+ = [(Fe +)2, Fes +, 89 , Mo" +]+, where (Fe +)2 is the delocalized Fe Fe pair. ... 

As hinted at previously, Vogel and coworkers have recently offered an alternative interpretation of what occurs when corroles are reacted with divalent metals." This work, which has been largely focused on nickel and copper, has served to call into question the structural and metal oxidation state assignments not only of the... 

Two successive, reversible one-electron reductions in the range from —2.0 to -3.1 V are observed for the [Ti(bpy)3] complex [111] these are attributed to the formation of [Ti(bpy)3], z = l-,2—. These species seem to undergo partial bpy dissociation in solution. Oxidation-state assignment to Ti and the bpy ligands is not completely clear. Both reduetions are assumed to be Ti-localized [111]. Indeed, the z = 1-,2-complexes have spectroscopic features [112, 113] of a bpy ligand whereas [Ti(bpy)3] probably contains a bpy ligand also [112]. 

The oxidation state assignment problem stems from the nature of the filled 4c level. The classical case of Re(VI) and a ligand unit of L3 corresponds to 4e being designated a ligand level. If 4e is more properly identified with the metal, the four electrons should be included with the... 

The mechanism of MMO including the different states of the iron dimer complex has been reviewed several times [66, 67, 68]. The lowest oxidation state of the diiron complex is Fe2(II,II) which is a loosely bound, ferro-magnetically coupled dimer with a long Fe-Fe distance. This complex, termed O, reacts with O2 to form another complex P, which is normally assigned to an Fe2(III,III) peroxide complex. One or more intermediates in between O and P have been postulated [70]. In the next step, the dioxygen bond is cleaved and an unprecedented Fe2(IV,IV) complex termed Q is formed. The oxidation state assignment was made based on Mbssbauer spectroscopy [71]. Compoimd Q has been suggested to be the active oxidant that attacks methane. 

Oxidation states are important when predicting the behaviour of elements or compounds. For example, chromium is quite insoluble and non-toxic as chromium (III), while as chromium (VI) it forms the soluble complex anion Cr042, which is toxic. As with most simple rules, those for oxidation state assignment apply to most but not all compounds. 

Oxidation states are a matter of debate, depending on the electron count, i.e. tiie nature attributed to the nitrogen ligand coordinated to vanadium. The oxidation states assigned here do not in all cases agree with those proposed in the original literature. 

The coordination chemistry of second-row transition metal corroles is less extensive than for first-row metals, but there are now numerous examples. The synthesis of brick red (oxo)Mo(mec) (mec = 2,3,17,18-tetramethyl-7,8,12,13-tetraethylcorrolate) was reported in a 1977 letter [63]. The first Ru corrole was synthesized as a cofacial Ru(III)-Ru(III) dimer in 2000 [64] the synthesis of a monomeric Ru corrole was achieved in 2003 [65]. A dicarbonylrhodium(I) A -me thy I corrole complex, where Rh(I) is bound to two of the ring nitrogen atoms, was reported in 1976 [66], while the synthesis of a Rh(III) corrole was published a dozen years later [67]. A series of Ag(III) corroles was described in 2003 [68]. This oxidation state assignment was supported by an X-ray photoelectron spectroscopy (XPS) comparison to cationic Ag(III) porphyrin complexes. 

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