Decomposition studies of group 6 hexacarbonyl complexes. Part 2: Modelling of the decomposition process

Abstract

Abstract:The decomposition behavior of group 6 metal hexacarbonyl complexes (M(CO) 6 ) in a tubular flow reactor is simulated. A microscopic Monte-Carlo based model is presented for assessing the first bond dissociation enthalpy of M(CO) 6 complexes. The suggested approach superimposes a microscopic model of gas adsorption chromatography with a first-order heterogeneous decomposition model. The experimental data on the decomposition of Mo(CO) 6 and W(CO) 6 are successfully simulated by introducing available thermodynamic data. Thermodynamic data predicted by relativistic density functional theory is used in our model to deduce the most probable experimental behavior of the corresponding Sg carbonyl complex. Thus, the design of a chemical experiment with Sg(CO) 6 is suggested, which is sensitive to benchmark our theoretical understanding of the bond stability in carbonyl compounds of the heaviest elements.

Complex chemistry with complex compounds

“…It was shown in Ref. [18] that the simplest approach addressing the stability on a molecular level would be thermal decomposition studies on a silver surface. A typical decomposition setup used for this purpose comprised a tubular flow reactor of 1 m length and 4 mm inner diameter entirely covered inside with thin silver foils.…”

“…[10,11]. A kinetic decomposition model was developed superimposing gas chromatographic transport of species through the open tubular reactor with heterogeneous decomposition of the species upon adsorption on the inner surfaces of the reactor [19]. This model was successfully applied to relate the decomposition observations to the FBDE given for the hexacarbonyl complexes [10,11].…”

“…3, lines). Therefore, it was also applied in reference [19] to predict the hypothetical decomposition interval for Sg(CO) 6 at the same experimental conditions (at 1 l/min gas flow rate) based on the theoretically predicted FBDE [10]. This prediction revealed the suggested method to be sensitive enough for a comparative study.…”

Chemistry aided nuclear physics studies

“…Recently, the in-situ chemistry of metal carbonyl complexes has been explored [14][15][16][17][18] and it is still under investigation (see contribution R. Eichler et al in this proceedings). Group 6 and group 8 elements were known to form volatile complexes with carbon monoxide.…”

“…Group 6 and group 8 elements were known to form volatile complexes with carbon monoxide. However, these complexes are not stable at temperatures of a few hundred degrees Celsius [18]. Direct synthesis in a recoil chamber behind the target is not possible due to the presence of a plasma induced by the primary beam.…”