Formal oxidation state analysis

In addition to the above oxides M2O, M2O2, M4O6, MO2 and MO3 in which the alkali metal has the constant oxidation state 4-1, rubidium and caesium also form suboxides in which the formal oxidation state of the metal is considerably lower. Some of these intriguing compounds have been known since the turn of the century but only recently have their structures been elucidated by single crystal X-ray analysis. Partial oxidation of Rb at low temperatures gives RbeO which decomposes above —7.3°C to give copper-coloured metallic crystals of Rb902 ... 

A structural classification of 8 is difficult due to the fact that an arrangement of metal atoms as in 8 is uncommon in the whole field of molecular metal clusters. For this reason, detailed understanding of the bonding properties in 8 requires quantum chemical calculations. Theoretical analysis seems to be especially applicable to learning more about the bond between the two tetrahedra, which appears at first to be an isolated metal-metal bond between two metal atoms in the formal oxidation state zero. 

The bis(oxalato)platinate(II) complexes based on [Pt(C204)2] , forms another family of linear chain systems, and the partially oxidised complex series, Cx[Pt(C204)2]-n(H20) (C = K, Rb, Mg " ", Co, Ni, Zn ), was reported.According to elemental analysis and X-ray diffuse scattering measurements, the formal oxidation state of platinum in this series is estimated in the range of -1-2.19 to -f2.38. The average Pt-Pt distance is 2.84-2.89 A and the conductivity at room temperature is 10 -10 S cm , depending on the associated cation. 

Contrary to expectation, the reaction product 8, a black amorphous powder soluble in water and acetic acid, was found to have composition and properties quite different from those expected for the platinum analog of the Pdsgi giant clus-ter.157] According to elemental analysis, substance 8 has the reproducible elemental composition Pt8phen3(0Ac)4(0H)4(H20)6, which is quite different from the expected minimum formula Pt9(phen)o.96(OAc)2.89 for the Pt analog of palladium giant cluster 6. On the basis of the elemental composition, the formal oxidation state of platinum in substance 8 is close to (+1). This value was confirmed by the EXAFS data. ... 

The existence of Ru(CO)s and Os(CO)5 has been confirmed by their IR spectra in heptane solution. Both compounds seem to be trigonal-bipyramidai. In the M(CO)4 series (Tj), p(CO) decreases and p(MC) increases in going from Ni(CO)4 to [Co(CO)4j to [Fe(CO)4 . This result indicates that the M -> CO 7r-back-donation is increasing in the order Ni(0) < Co(--l) < Fe(—II). Highly reduced species such as Na4[M(CO)4) (M = Cr, Mo, and W of formal oxidation state, —IV) exhibit very low p(CO) (1530-1460 cm ). Edgell and co-workers " attributed the band at 413 cm of Li(Co(CO)4] in a THF solution to the vibrations of the alkali ions, which form ion pairs with [Co(C0)4]" For sodium and potassium salts, the corresponding bands are observed at 192 and 142 cm , respectively. Based on computer-aided curve analysis of IR spectra of Na[Co(CO)4] in the p CO) region, they also demonstrated that there are three kinds of ion sites in THF solution each of which exhibits different spectra. Their structures and p(CO) are shown in Fig. 111-39. 

The spectacular iridium compound HH,HT,HH-[Ir6(/t-OPy)6(I)2(CO)i2] 231 containing an unprecedented almost linear metal chain made up of six iridium atoms has been prepared by Tejel et al. by oxidation of [Ir2(/t-OPy)2(CO)4] with iodine at 0°C in toluene. The formal oxidation state of the iridium atoms is 1.33. The new hexairidium compound has been characterized by X-ray diffraction analysis showing a linear array of iridium-bonded atoms with an HT-[Ir2(/t-OPy)2(CO)4] complex sandwiched in between two HH-[Ir2(/t-OPy)2(I)(CO)4] units (Figure 18). Complex 231 represents the longest polyiridium chain complex so far know. Other polyiridium species with as many as four iridium atom chain have been reported, see Ref 112,112a,l 12b... 

Some insight into the methodological challenges in theoretical studies of f elements can already be gathered from looking at the uranyl double cation UO l which is a closed-shell molecule important in the treatment of nuclear waste. In this molecule the uranium atom has formal oxidation state + W, but from projection analysis [55] at the HF level we find a charge of -1-2.94 and configuration 5/ - 7/ of the uranium atom in the molecule. 

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