EXAFS Study of Ph 3 GeMn(CO) 5 Structure Evolution on Exposure to X-Radiation

Abstract

Ge K-edge and Mn K-edge EXAFS spectroscopy was used to study changes in the local environment of germanium and manganese atoms during radiolysis of the Ph3GeMn(CO)5 complex. On exposure to X-radiation, the metal complex undergoes a number of transformations depending on the radiant exposure (Φ). It was shown that at Φ = (6–8) × 106 J/m2, the initial metal complex decomposes into the [Ph3Ge] and [Mn(CO) n ] fragments with partial detachment of the CO groups from Mn atoms. When Φ = 1.3 × 107 J/m2, Mn atoms lose completely the CO groups to form finely dispersed metal nanoparticles, which interact with the surrounding atoms (carbon or nitrogen). With further increase in Φ, the local environment of the Mn atoms no longer changes. The Ge atoms remain coordinated to the Ph groups as Φ increases up to 2 × 107 J/m2, but starting with Φ = 1.6 × 107 J/m2, metal–metal bonds are formed; subsequently, the amount of this phase increases and when Φ = 2.6 × 108 J/m2, it becomes predominant. Since manganese and germanium atoms lose their ligands at different Φ values, one can conclude that germanium and manganese nanoparticles are the final products in the radiolysis of Ph3GeMn(CO)5.