Molybdenum complexes spectral indicators

Norbornadiene (NBD) in (NBD)M(CO)4 (353) is readily displaced by CO (274) or (2-allylphenyl)(diphenyl)phosphine (50, 312). Although the latter reaction gives the compound of expected composition, (C2iHi9P)M(CO)4, both the chemical and spectral data indicate that it has the structure (26) in which the C21H19P ligand is the isomeric (2-propenyl)(diphenyl)phosphine. For the molybdenum complex this structure has been confirmed by X-ray diffraction (379). 

Thus, on the basis of the spectral data alone we cannot draw a conclusion concerning the preferable dissolution order of the above mentioned elements. However, the absence of absorption peaks of MoClg , NiCl4 , TiCls " complex ions indicates that these elements do not transfer to the electrolyte during the anodic dissolution of steel. This was also confirmed by the results of the chemical analysis of melt samples. From the electrochemistry point of view, the fact that electropositive nickel [30] and molybdenum [31] remain in the anode material points to the electrochemical nature of the corrosion process. The results of the spectroscopy measurements and chemical analysis were confirmed by X-ray microanalysis - the electrode surface after 2 h of anodic dissolution was slightly depleted in iron and chromium and was enriched in nickel. 

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