Platinum zero oxidation state

Compounds of the elements in zero oxidation state are known for all three metals. With one exception, those of nickel contain the equivalent of four ligands coordinated to the metal, whereas palladium and platinum also fonn compounds of empirical formulas ML2 and ML3 (162-164). 

Compounds of palladium and platinum in zero oxidation state are no longer rare, but there is little or no structural information available. The best ligands seem to be isonitriles, tertiary phosphines, and tertiary arsines (162-164) compounds of platinum(O) with ammonia and ethylenedi-... 

Elements of this group, like metals of groups 8 and 9, form mononuclear and cluster homoleptic complexes in which metals adopt a zero oxidation state. The following homoleptic complexes of these elements are known [M(CNR)4] (M = Ni, Pd, Pt), [Ni(CNR)4], [Ni4(CNR),], [Ni4(CNR)4] , [NigiCNR). ], [Ni4(CNR)i4](C104)s, and [Ni3(CNR),i](C104)6. Linear structures were assigned for the last two compounds.Monomeric platinum and palladium compounds... 

Silica-supported platinum catalysts with a thin film of [C4dmim][OTf] (l-butyl-2,3-dimethylimidazolium trifluoromethanesulfonate) were investigated by the Lercher group, with a focus on the interactions between ionic liquid, support and platinum particles [83]. The interaction of silica and the ionic liquid occurs via hydrogen bonds. Platinum clusters modify the electron density of the ionic liquid, which changes the polarity of the ionic liquid within certain levels. The ionic liquid protects the platinum cluster from oxidation, as the platinum particles in ionic liquid-coated systems are in the zero oxidation state. SCILL-catalysed ethene hydrogenation showed that the interaction of the ionic liquid with the platinum surface is weaker than the interaction of ethene and the platinum surface. 

Next question concerns the oxidation state of platinum in Pt/SDB catalysts. Admittedly, X-ray diffraction pattern presented in Ref [12] clearly indicated the presence of Pf, but small amounts of other platinum species (undetected by X-ray technique) possibly can also exist on the catalyst surface. Temperature-programmed reduction profile of SDB-supported R(acac)2 contained two peaks, the first of which corresponded to the reaction of hydrogen with of platinum(Il) acetylacetonate and the second one to the reaction between hydrogen and products of partial decomposition of R(acac)2. X-ray photoelectron spectroscopy (XPS) measurements carried out in the present study have shown the presence of platinum species in the +2 oxidation state, in addition to those in zero oxidation state (Table 15.4). 

Xenon is noncombustible, and even though it is considered inert, it will combine with a few elements (i.e., oxygen, fluorine, and platinum). Xenon is the only member of group 18 that exhibits all of the even valence states of +2, +4, +6, and +8. It has similar oxidation states even though most periodic tables list a single oxidation state of zero. 

Tertiary phosphine complexes of the platinum metals Complexes in which the metal has an oxidation state of zero... 

By way of example, we can focus on the cyano complexes. Palladium and platinum can form homoleptic complexes with two, four, or six cyanides, depending on the metal oxidation state zero, two, and four, respectively. Rhenium forms heptacyano complexes in its - -3 and -t-4 oxidation states but forms an octacyano complex in its -t-5 state. Molybdenum and tungsten also appear commonly in octacyano complexes for +4 and - -5 oxidation states, and heptacyano analogs for the - -2 and - -3 cases, with only one occurrence of [Mo(CN)6]" anions in two oxidation states (n = 3, 4). Similar situations can be found with phosphine or carbonyl complexes. For instance, the group... 

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