Why Are (MgO)_n Clusters and Crystalline MgO So Reactive?

Abstract

The electronic structures and chemical reactivities (toward H, Li, Li 2 , and H 2 ) are examined for small (MgO) n clusters. It is postulated that decreases in the clusters' reactivity toward the above prototypical species as the cluster size (n) increases is related to the decrease in valence unsaturation that accompanies increases in n. Further, it is suggested that the known high reactivity of MgO powder and crystal is likely related to surface or defect sites that possess high levels of valence unsaturation.

Small Group IIa–VIa Clusters and Related Systems: A Theoretical Study of Physical Properties, Reactivity, and Electronic Spectra

“…This agrees well with the remarkable reactivity of MgO. [31] Again, the features of the species that include first-row ele- D), electric dipole moments, µ(E, F), and energies of frontier orbitals, E(G, H) for 25 group IIa-VIa diatomics: oxides, sulfides, selenides, tellurides, polonides of beryllium, magnesium, calcium, strontium, and barium, respectively. Computational methods and units used are indicated in the graphs.…”

Low‐Temperature Activation of Methane: It also Works Without a Transition Metal

“…Accordingly, the reactions of diatomic MgO as well as several model clusters have been studied extensively by means of theory. [5][6][7][8][9] Theory strongly suggests that the cationic species [MgO] + should effectively activate methane, [10,11] and also for neutral MgO the computed activation barrier is rather low. [9] Accordingly, the elementary steps in the chemistry of magnesium and its oxides have received considerable attention in several experimental studies, [12][13][14][15][16][17][18][19] yet a decisive route for the generation of ionic species such as [MgO] + in amounts sufficient for subsequent reactivity studies has not been achieved to date.…”

Thermische Aktivierung von Methan: Es geht auch ohne Übergangsmetalle

“…Dementsprechend sind die Reaktionen von zweiatomigem MgO sowie von verschiedenen Modell-Clustern intensiv theoretisch untersucht worden. [5][6][7][8][9] Die theoretischen Studien sagen vorher, [10,11] dass die kationische Spezies [MgO] + Methan sehr effizient aktivieren sollte, und für neutrales MgO ist die berechnete Aktivierungsbarriere ebenfalls niedrig. [9] Auch experimentell sind die Elementarschritte in der Chemie des Magnesiums und seiner Oxide vielfach untersucht worden, [12][13][14][15][16][17][18][19] [20] von wässrigen Magnesium(II)-nitrat-Lösungen bei härteren Ionisierungsbedingungen vor und berichten erstmals von der Gasphasenreaktivität dieses Kations.…”